WO2018040904A1

WO2018040904A1 - Polymer composite film and preparation method therefor and lithium ion battery comprising the polymer composite film

Info

Publication number: WO2018040904A1
Application number: PCT/CN2017/097405
Authority: WO
Inventors: 胡家玲; 单军; 吴金祥; 何龙
Original assignee: 比亚迪股份有限公司
Priority date: 2016-08-29
Filing date: 2017-08-14
Publication date: 2018-03-08
Also published as: US11264674B2; US20210288381A1; KR102177633B1; KR20190033090A; EP3493297A4; JP6878571B2; JP2019526899A; EP3493297A1; EP3493297B1; CN107785519A

Abstract

A polymer composite film and a preparation method therefor and a lithium ion battery using the polymer composite film. The polymer composite film comprises a porous base film and a heat-resistant fiber layer covering on at least one side surface of the porous base film; the material of the heat-resistant fiber layer contains a first high polymer material and a second high polymer material simultaneously; the first high polymer material is a heat-resistant high polymer material having a melting point higher than 180℃; and the second high polymer material has a melting point lower than that of the first high polymer material, and the second high polymer material, in electrolyte solution at 25℃, has an electrolyte uptake of greater than 40% with an error of ±5%. The first high polymer material and the second high polymer material are used to form the heat-resistant fiber layer, so that transport of lithium ions cannot be blocked; therefore, the ionic conductivity of the polymer composite film is maintained and performances such as the cycle life and the like of the battery are further prolonged to a certain extent.

Description

Polymer composite film, preparation method thereof and lithium ion battery including the same

Cross-reference to related applications

The present disclosure claims priority to Chinese Patent Application No. 201610750354.7, filed on Jan. 29,,,,,,,,

Technical field

The present disclosure relates to the field of lithium ion batteries, and in particular to a polymer composite membrane and a method of preparing the same; the present disclosure also includes a lithium ion battery using the foregoing polymer composite membrane.

Background technique

Lithium-ion batteries are mainly composed of positive/negative materials, electrolytes, separators and battery casing packaging materials. The separator is an important component of the lithium ion battery, which serves to separate the positive and negative electrodes and prevent the internal short circuit of the battery; it allows the electrolyte ions to pass freely, and completes the electrochemical charging and discharging process. Its performance determines the interface structure and internal resistance of the battery, which directly affects the rate performance, cycle performance and safety performance (high temperature resistance) of the battery. The separator with excellent performance plays an important role in improving the overall performance of the battery. It is called the "third electrode" of the battery.

The preparation methods of the traditional diaphragm mainly include two types: "melt stretching method" and "thermal phase separation method". Among them, the "melt stretching method" is prepared by crystallizing a polymer melt such as polyolefin under high stress field. Forming a platelet structure having a direction perpendicular to the extrusion direction and parallel alignment, and then heat-treating to obtain a so-called hard elastic material. After the polymer film having hard elasticity is stretched, the platelets are separated, and a large amount of microfibers are formed, thereby forming a large number of microporous structures, and then heat-setting forms a microporous film. Among them, "thermal induced phase separation method" is a method for preparing microporous membrane developed in recent years, which utilizes high polymer such as polyolefin and some high boiling small molecule compounds at a relatively high temperature (generally higher than polymerization) When the melting temperature of the substance is Tm), a homogeneous solution is formed, and the temperature is lowered to cause solid-liquid or liquid-liquid phase separation, so that the additive phase is contained in the polymer-rich phase, and the polymer phase is contained in the rich phase. After the stretching, the low molecular substances are removed to form a microporous membrane material which penetrates each other.

However, the separator prepared by the "melt drawing method" has a relatively low cost, relatively good mechanical strength (toughness and strength), but poor high temperature stability (heat shrinkage); and "thermal phase separation" The separator prepared by the method has improved in high temperature stability, but its cost is relatively high, and the mechanical strength of the material is deteriorated (hardened), which limits its development in the field of batteries.

R&D personnel are always looking for a way to balance the mechanical strength and high temperature stability of the diaphragm to suit the electricity The rapid development of the pool industry.

Summary of the invention

It is an object of the present disclosure to provide a polymer composite film, a method of preparing the same, and a lithium ion battery including the same, to balance the mechanical strength and high temperature thermal stability of the polymer composite film.

In order to achieve the above object, according to a first aspect of the present disclosure, there is provided a polymer composite film comprising a porous base film and a heat resistant fiber layer covering at least one surface of the porous base film The material of the heat resistant fiber layer simultaneously contains a first polymer material and a second polymer material; the first polymer material is a heat resistant polymer material having a melting point of 180 ° C or higher; the second polymer The melting point of the material is lower than the first polymer material, and the liquid absorption rate of the second polymer material in the electrolyte solution at 25 ° C is 40% or more with an error of ± 5%.

According to a second aspect of the present disclosure, there is provided a method for preparing a polymer composite film, the method comprising the steps of: S1, providing a porous base film; S2, preparing a first polymer material and a second polymer material Spinning solution, the spinning solution is formed by electrospinning on at least one side surface of the porous base film to form a heat resistant fiber layer; the first polymer material has a heat resistance higher than a melting point of 180 ° C or higher a molecular material; the second polymer material has a melting point lower than the first polymer material, and the second polymer material has a liquid absorption rate of 40% or more in an electrolyte solution at 25° C., and an error of ±5 %.

According to a third aspect of the present disclosure, there is provided a lithium ion battery comprising a positive electrode, a negative electrode, and a battery separator between the positive and negative electrodes, the battery separator being a polymer of the present disclosure Composite film.

The use of the polymer composite film of the present disclosure, a method for preparing the same, and a lithium ion battery including the same have the following beneficial effects:

(1) By using a heat-resistant polymer material as the first polymer material, it is advantageous to improve the high temperature resistance (transverse/longitudinal heat shrinkage rate) of the polymer composite film, so that the polymer composite film is at a high temperature (180 ° C) The heat shrinkage is small, which is beneficial to avoid the positive and negative contact caused by the shrinkage of the polymer composite film caused by the heat generation of the battery (for example, caused by a small short circuit), thereby ensuring the high temperature and safety performance of the battery.

(2) By using a second polymer material having a liquid absorption rate of 40% or more at 25 ° C, the second polymer material can be swelled and swelled in the electrolyte solution, and partially gelled, so that gelation is achieved. The second polymer material has a certain viscosity, which is beneficial to enhance the phase between the heat resistant fiber layer and the ceramic layer, and/or between the heat resistant fiber layer and the outer layer structure (bonding layer or positive and negative electrodes) Capacitance, enhancing the bonding force between the heat resistant fiber layer and the ceramic layer, and/or between the heat resistant fiber layer and the outer layer structure (bonding layer or positive and negative electrodes), is advantageous for improving the prepared polymer composite Mechanical properties of the film at high temperatures.

(3) by using the first polymer material and the second polymer material simultaneously, the first polymer has a higher melting point (in 180 ° C or more), can maintain good strength at high temperature, making it the skeleton of the entire spinning fiber network structure; and using the second polymer material (25 ° C liquid absorption rate of 40% or more) in the electrolyte It can absorb liquid and swell, and partially gelatinizes, so that the gelled second polymer material has a certain viscosity, and then adheres to the skeleton of the spun fiber network structure formed by the first polymer material, The skeleton of the spinning fiber network structure plays a certain reinforcing role, thereby improving the mechanical strength (transverse tensile strength, longitudinal tensile strength and needle punching strength) of the heat resistant fiber layer and the polymer composite film.

(4) forming a heat-resistant fiber layer by using the first polymer material and the second polymer material, the heat-resistant fiber layer having a network structure of the spun fiber, which causes gelation of the second polymer material The material layer (thinner) is attached to the surface of the first polymer material, so it does not hinder the migration of lithium ions, and is beneficial to maintaining the ionic conductivity of the polymer composite film, thereby improving the cycle life of the battery to some extent. Performance.

Other features and advantages of the present disclosure will be described in detail in the Detailed Description of the Detailed Description.

DRAWINGS

The drawings are intended to provide a further understanding of the disclosure, and are in the In the drawing:

1 shows an SEM picture of a polymer composite film F1 obtained according to Example 1 of the present disclosure, at a magnification of 2000 times.

detailed description

Specific embodiments of the present disclosure are described in detail below. It is to be understood that the specific embodiments described herein are not to be construed

The endpoints and any values of the ranges disclosed in the disclosure are not limited to the precise range or value, and such ranges or values are understood to include values that are close to the ranges or values. For numerical ranges, the endpoint values of the various ranges, the endpoint values of the various ranges and the individual point values, and the individual point values can be combined with one another to yield one or more new ranges of values. The scope should be considered as specifically disclosed herein.

In the present disclosure, there is provided a polymer composite film comprising a porous base film and a heat resistant fiber layer covering at least one side surface of the porous base film, a material of the heat resistant fiber layer The first polymer material and the second polymer material; the first polymer material is a heat resistant polymer material having a melting point of 180 ° C or higher; and the melting point of the second polymer material is lower than the first The polymer material and the second polymer material have a liquid absorption rate of 40% or more in an electrolytic solution at 25 ° C, and may be 40-100%, and the error is ±5%. In the present disclosure, the error of ±5% here means that the test is under test. The error in the liquid absorption rate of the second polymer material.

The term "liquid absorption rate" measuring method in the present disclosure includes: dissolving a material to be tested in a corresponding solvent, casting a sample of a specified size (for example, a disk having a diameter of 17 mm), and drying it in an argon-filled glove box ( In 25 ° C), the sample mass m1 is weighed, and then the sample is immersed in an electrolyte (the electrolyte contains a lithium salt LiPF ₆ (lithium hexafluorophosphate) and an organic solvent system, and the content of the lithium salt is 1 mol/L, the organic solvent The system contains 32.5% by weight of EC (ethylene carbonate), 32.5% by weight of EMC (ethyl methyl carbonate), 32.5% by weight of DMC (dimethyl carbonate), based on 100% by weight of the total amount. 2.5 wt% of VC (vinylene carbonate) in 24 h, then take out the sample, use a filter paper to dry the liquid on the surface of the sample (without pressing), and weigh the mass m2 of the sample, then according to the formula "liquid absorption rate = (m2-m1) / m1 × 100%", the corresponding liquid absorption rate is calculated. During the measurement of the liquid absorption rate, different operators may operate differently on the step of “drying the surface liquid of the sample with filter paper”, which may affect the measurement results, and allow measurement in the present disclosure. The error is ±5%.

According to the polymer composite film of the present disclosure, in an embodiment, the first polymer material has a liquid absorption rate of less than 5% in an electrolyte at 25 ° C with an error of ± 5%; by controlling the first polymer The liquid absorption rate of the material is beneficial to better maintain the skeleton of the spun fiber network structure formed by the first polymer material under high temperature condition, and optimize the heat resistance stability of the prepared polymer composite film (heat resistant safety) Sex).

According to the polymer composite film of the present disclosure, in an embodiment, the first polymer material has a glass transition temperature of 100 ° C or higher. By selecting the first polymer material having a glass transition temperature of 100 ° C or higher, it is advantageous to optimize the prepared polymer composite film to maintain a high strength during the temperature increase process (room temperature to 100 ° C), so that the electrolyte is passed through the electrolyte. The second polymer material capable of absorbing liquid swelling and partially gelling can be better integrated on the skeleton of the spun fiber network structure formed by the first polymer material, thereby optimizing the prepared polymer composite The heat resistance of the film.

According to the polymer composite film of the present disclosure, in an embodiment, the optional first polymer material includes, but is not limited to, polyetherimide (PEI), polyetheretherketone (PEEK), polyethersulfone (PES). One or more of polyamideimide (PAI), polyamic acid (PAA), and polyvinylpyrrolidone (PVP). Among them, polyetheretherketone (PEEK) includes copolyetheretherketone (CoPEEK) and modified polyetheretherketone, as long as the melting point of the polyetheretherketone satisfies the above requirements.

Specifically, the first polymer material that can be used includes, but is not limited to, polyetherimide ultem1000 commercially available from SABIC Innovative Plastics (Shanghai) Co., Ltd. (glass transition temperature is 215 ° C, in an electrolyte at 25 ° C) The liquid absorption rate is 0.1%), the K90 grade polyvinylpyrrolidone product commercially available from Hangzhou Shenhua Company (the glass transition temperature is 110 to 130 ° C, the liquid absorption rate in the electrolyte at 25 ° C is 1%), One or more of the ketaspire brand polyetheretherketone products (the glass transition temperature is 143 ° C and the liquid absorption rate in the electrolyte at 25 ° C is 0.5%).

According to the polymer composite film of the present disclosure, in an embodiment, the second polymer material has a melting point of 100 to 150 ° C; the second polymer material has a glass transition temperature of 25 ° C or less; by selecting vitrification Lower temperature The second polymer material can facilitate the softening of the second polymer material at the normal use temperature of the battery (room temperature to 40 ° C), and is bonded to the structure of the spun fiber network formed by the first polymer material. On the skeleton, the heat resistance stability of the prepared polymer composite film is further optimized. In an embodiment, the optional second polymeric material includes, but is not limited to, one or more of modified polyvinylidene fluoride (PVDF), polyacrylate, polystyrene, and polyethylene oxide (PEO). .

It should be noted that, in the present disclosure, the second polymer material may be a raw material of the above type (modified polyvinylidene fluoride, polyacrylate, polystyrene, and polyethylene oxide), but the prerequisite is that the raw materials used are The liquid absorption requirements of the second polymeric material of the present disclosure must be met. Taking polyvinylidene fluoride as an example, the generally unmodified polyvinylidene fluoride has a liquid absorption rate of 10-20%, which does not meet the use requirements of the present disclosure, and the present disclosure selects to modify the liquid absorption by modification. A modified polyvinylidene fluoride satisfying the above requirements, such as polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP); in the case of polyacrylate, a polyacrylate having a liquid absorption rate satisfying the above requirements includes, but not limited to, polyacrylic acid. Methyl ester, polymethyl methacrylate and polyethyl acrylate.

Specifically, the second polymer material that can be used includes, but is not limited to, the LBG grade PVDF-HFP product commercially available from Acme (the glass transition temperature is -55 to -40 ° C, in an electrolyte at 25 ° C). The liquid absorption rate is 45-60%), commercially available from Aladdin's polyoxyethylene product (glass transition temperature is -65 ° C, the liquid absorption rate in the electrolyte at 25 ° C is 1000%, Mw = 600,000), One or more of commercially available polymethyl methacrylate products (absorbency in an electrolyte at 25 ° C of 55%). Optionally, the second polymer material has a liquid absorption rate of 40 to 100% at 25° C., and an error of ±5%.

According to the polymer composite film of the present disclosure, there is no limitation on the selection of materials in the heat resistant fiber layer. On the basis of using the first polymer material and the second polymer material at the same time, reference may also be made to the conventional material requirements in the art. Appropriate addition of other raw materials, such as nano ceramic particles, etc. Of course, the material of the heat resistant fiber layer in the present disclosure may also be composed of a blend of the first polymer material and the second polymer material. The effect desired by the present disclosure can be better achieved by using the blend of the first polymer material and the second polymer material for preparing the heat resistant fiber layer of the polymer composite film of the present disclosure.

According to the polymer composite film of the present disclosure, the weight ratio of the first polymer material to the second polymer material in the heat resistant fiber layer may be arbitrary as long as the specific first polymer material is the main raw material, Part of the second polymeric material is capable of achieving the objects of the present disclosure to some extent. However, considering the temperature stability and strength and toughness of the entire polymer composite film, the weight ratio of the first polymer material to the second polymer material in the heat resistant fiber layer may be selected from 0.5 to 10 in the present disclosure. :1, optional from 1 to 5:1, optionally from 1 to 3:1.

According to the polymer composite film of the present disclosure, in an embodiment, the first polymer material in the heat resistant fiber layer is polyetherimide, and the second polymer material is polyvinylidene fluoride-hexafluoropropylene; The material of the fiber layer is polyetherimide and poly A blend of vinylidene fluoride-hexafluoropropylene. Polyetherimide can maintain good strength at high temperature, making it the backbone of the entire spinning fiber network structure, while polyvinylidene fluoride-hexafluoropropylene can absorb and swell in the electrolyte, with gelation. The characteristics thus have a certain adhesiveness, and thus can adhere well to the skeleton of the spun fiber network structure formed by the polyetherimide, and the skeleton of the spun fiber network structure can be enhanced. Further, the mechanical strength of the first heat-resistant fiber layer and the polymer composite film is improved.

According to the polymer composite film of the present disclosure, in the above polymer composite film, the heat resistant fiber layer has a porosity of 70% or more, and optionally the heat resistant fiber layer has a porosity of 70 to 70. 95%, for example 75 to 95%. The heat-resistant fiber layer has a high porosity and can effectively ensure the ionic conductivity of the polymer composite film. In the present disclosure, the porosity of the heat-resistant fiber layer is measured by preparing a sample of a heat-resistant fiber layer of a specific size, weighing, and then immersing the heat-resistant fiber layer sample in isobutanol, and measuring the sample weight after adsorption equilibrium. Through the formula:

The porosity of the heat resistant fiber layer was calculated.

According to the polymer composite film of the present disclosure, in an embodiment, the heat resistant fiber layer has an areal density of 0.2 to 15 g/m ² , optionally 3 to 6 g/m ² . The heat-resistant fiber layer density refers to the mass of the material applied to the substrate membrane per unit area. In the present disclosure, when the areal density of the heat-resistant fiber layer is within the above range, the electrical conductivity can be effectively ensured, the lithium ion migration is not affected, and the bonding performance is better, which is advantageous for improving the safety performance of the battery.

The polymer composite film according to the present disclosure, wherein the thickness of the heat resistant fiber layer and the diameter of the fiber therein are not particularly limited, and in the embodiment, the heat resistant fiber layer has a single side thickness of 0.5 to 30 μm, optionally 1 -20 μm; in an embodiment, the fiber has a diameter of from 100 to 2000 nm. In the present disclosure, when the thickness of the heat resistant fiber layer is within the above range, the positive and negative electrodes and the separator can be effectively bonded to improve the cycle performance of the battery.

The polymer composite film according to the present disclosure, wherein the heat resistant fiber layer may be formed on one side surface of the porous base film, and also formed on both side surfaces of the porous base film. In an embodiment, the heat resistant fiber layer is formed on both sides of the porous base film.

The polymer composite film according to the present disclosure, wherein the porous base film may be a polymer base film or a ceramic separator, wherein the polymer base film may be a polyolefin separator common to lithium ion batteries, including, but not limited to, poly a propylene (PP) separator, a polyethylene (PE) separator, and a PE/PP/PE three-layer separator or the like; the ceramic separator is the same as a ceramic separator conventional in the art, and includes a polymer base film (identical to the foregoing) and at least A ceramic layer on one side surface of the polymer base film.

According to the polymer composite film of the present disclosure, in an embodiment, the porous base film is a ceramic separator, wherein there is no particular requirement for the ceramic layer in the ceramic separator, and a ceramic layer conventionally employed in the art may be selected. However, the inventors of the present disclosure have found through intensive research that the prior art generally makes the ceramic layer of the ceramic separator intentionally or unintentionally made into a low density and high porosity, although this can greatly increase the gas permeability of the ceramic separator, but such a ceramic The separator is difficult to withstand high temperatures, and significant heat shrinkage usually occurs above 160 °C, which affects the safety performance of the battery. In addition, although it is mentioned in CN105355825A that the surface density of the ceramic layer can be controlled between 0.2 and 1.8 mg/cm ² to improve its pressure resistance and ion permeability, the surface density does not eliminate the thickness factor, that is, The increase in areal density may result from the thickening of the ceramic layer, rather than the fact that the ceramic layer is more densely packed. Such an increase in areal density can improve the safety by improving the thermal resistance of the ceramic diaphragm, but its high temperature resistance and shrinkage resistance. Not ideal, and the increase in thickness also adversely affects battery capacity.

The inventors of the present disclosure have further found that when the ceramic layer of the ceramic separator has a areal density ρ at a unit thickness (1 μm) controlled at 1.8 mg/cm ² <ρ ≤ 2.7 mg/cm ² , the corresponding ceramic separator Has very excellent heat resistance and heat shrinkage. Based on this, in the present disclosure, the ceramic layer may be selected to contain ceramic particles and a binder, and the areal density ρ of the ceramic layer at a unit thickness (1 μm) satisfies 1.8 mg/cm ² < ρ 2.7 mg/cm. ² , optionally satisfying 1.85 mg/cm ² ≤ ρ ≤ 2.65 mg/cm ² , optionally satisfying 1.9 mg/cm ² ≤ ρ ≤ 2.6 mg/cm ² .

The preparation method of the ceramic separator provided by the present disclosure controls the optimal dispersion of the ceramic particles by controlling the amount of each component in the slurry of the ceramic layer, the number average molecular weight of the dispersant, and the rotational speed of the slurry forming the ceramic layer, thereby controlling the bulk density between the ceramic particles. The surface density of the ceramic layer at a unit thickness (1 μm) is controlled to 1.8 mg/cm ² <ρ ≤ 2.7 mg/cm ² , which can improve the high temperature heat shrinkage of the ceramic separator without substantially reducing the gas permeability. The heat resistance temperature is above 160 ° C, that is, the thermal stability energy is improved without increasing the thickness of the ceramic layer, thereby not affecting the energy density of the battery.

According to the polymer composite film of the present disclosure, in the embodiment, the binder is contained in an amount of 2 to 8 parts by weight, optionally 4, per 100 parts by weight of the ceramic particles. Up to 6 parts by weight. When the content of each substance in the ceramic layer is controlled within the above optional range, the obtained ceramic separator can have better high temperature heat shrinkage resistance and gas permeability.

According to the polymer composite film of the present disclosure, the kind of the ceramic particles may be a conventional choice in the art, and for example, may be selected from the group consisting of Al ₂ O ₃ , SiO ₂ , BaSO ₄ , BaO, TiO ₂ , CuO, MgO, Mg ( OH) ₂ , LiAlO ₂ , ZrO ₂ , CNT, BN, SiC, Si ₃ N ₄ , WC, BC, AlN, Fe ₂ O ₃ , BaTiO ₃ , MoS ₂ , α-V ₂ O ₅ , PbTiO ₃ , TiB ₂ One or more of CaSiO ₃ , molecular sieves, clay, boehmite and kaolin. In addition, the average particle diameter of the ceramic particles may be selected from 200 nm to 800 nm, and may be selected from 300 nm to 600 nm, which is advantageous for avoiding agglomeration of the slurry for forming the ceramic layer and for improving the gas permeability of the ceramic separator.

According to the polymer composite film of the present disclosure, the kind of the binder in the ceramic layer is not particularly limited, and may be various materials which can be used to increase the strength of the ceramic separator, for example, may be polyacrylate (optional) a copolymer having a weight average molecular weight M _{w of} from 1 × 10 ⁴ to 1 × 10 ⁶ g / mol), polyvinylidene fluoride and hexafluoropropylene (optional weight average molecular weight M _{w of} from 1 × 10 ⁴ to 1 × 10 ⁶ g /mol), a copolymer of polyvinylidene fluoride and trichloroethylene (optional weight average molecular weight M _w is 1 × 10 ⁴ to 1 × 10 ⁶ g / mol), polyacrylonitrile (optional weight average molecular weight M _w is 1×10 ⁴ to 1×10 ⁶ g/mol), polyvinylpyrrolidone (optional weight average molecular weight M _w is 1×10 ⁵ to 1×10 ⁶ g/mol), polyimide (optional weight average) The molecular weight M _w is 1×10 ⁴ to 1×10 ⁶ g/mol), and the polyvinyl alcohol (optional weight average molecular weight M _w is at least one of 1×10 ³ to 1×10 ⁵ g/mol, etc.) The polyacrylate is selected as the polyacrylate having a glass transition temperature of -40 ° C to 0 ° C. The polyacrylate having a glass transition temperature of -40 ° C to 0 ° C may specifically be methyl (meth)acrylate. , ethyl (meth)acrylate, butyl (meth)acrylate, ( At least one of a homopolymer, a copolymer, and the like of hexyl methacrylate. When a polyacrylate having a glass transition temperature of -40 ° C to 0 ° C is used as a binder, the ceramic separator can be not affected. On the basis of the bond strength, the processability is improved, and the industrial application prospect is further. Further, a crosslinkable monomer such as hydroxymethyl group and/or methylol group may be optionally introduced into the above polyacrylate binder. Acrylamide, and the content of the crosslinkable monomer can be optionally controlled within 8 wt%, optionally controlled at 3 to 5 wt%, which can cause light crosslinking of the polyacrylate binder, thereby improving ceramics The water resistance of the separator increases the bond strength of the ceramic layer.

According to the polymer composite film of the present disclosure, in the ceramic layer, the ceramic layer includes 2 to 8 parts by weight of the binder, and 0.3 to 1 part by weight of the dispersion with respect to 100 parts by weight of the ceramic particles. a 0.5 to 1.8 parts by weight of a thickening agent, and 0 to 1.5 parts by weight of a surface treating agent, and the number average molecular weight of the dispersing agent is 50,000 or less; alternatively, in the ceramic layer, relative to 100 parts by weight of the ceramic particles, the binder is used in an amount of 4 to 6 parts by weight, the dispersant is used in an amount of 0.4 to 0.8 parts by weight, and the thickener is used in an amount of 0.7 to 1.5 parts by weight, The surface treatment agent is used in an amount of from 0 to 1.5 parts by weight, and the dispersant has a number average molecular weight of from 5,000 to 20,000 g/mol.

According to the polymer composite film of the present disclosure, the type of the dispersant in the ceramic layer is not particularly limited, and various types of conventional materials which contribute to the dispersion of each substance in the ceramic layer slurry may be used, and the number average molecular weight may be 50,000 or less. Selected as at least one of polyacrylate, polyethylene glycol ether, silicate, phosphate and guar, optionally in polyacrylate, aliphatic polyethylene glycol ether, phosphate At least one. The polyacrylate may be, for example, at least one of potassium polyacrylate, sodium polyacrylate, lithium polyacrylate, and the like. The aliphatic polyglycol ether may be, for example, polyethylene glycol tert-octylphenyl ether and/or polyethylene glycol monolauryl ether. The phosphates may, for example, be sodium trimetaphosphate and/or sodium hexametaphosphate.

According to the polymer composite film of the present disclosure, the kind of the thickener in the ceramic layer is not particularly limited, and may be selected from the group consisting of polyacrylate, polyacrylate copolymer, polyvinylpyrrolidone, cellulose derivative, and polyacrylamide. At least one of them may be at least one selected from the group consisting of polyacrylates, polyacrylate copolymers, and cellulose derivatives. The polyacrylate may be, for example, at least one of potassium polyacrylate, sodium polyacrylate, lithium polyacrylate, and the like. The polyacrylate copolymer may be, for example, at least one of a copolymer of acrylic acid and styrene, a copolymer of acrylic acid and ethyl acrylate, a copolymer of acrylic acid and ethylene, and the like. The cellulose derivative may be, for example, at least one of sodium carboxymethylcellulose, potassium carboxymethylcellulose, hydroxyethylcellulose, and the like. In addition, the viscosity of the 1% by weight aqueous solution of the thickener is 1500 to 7000 mPa·s, which can be well dispersed in the ceramic layer slurry, and is favorable for coating, and is more favorable for the improvement of the areal density. Further, although both the dispersant and the thickener may be polyacrylates, polyacrylic acid as a thickener The number average molecular weight of the enoate is much higher than the molecular weight of the polyacrylate as a dispersing agent, and the number average molecular weight of the polyacrylate as a thickener is usually from 300,000 to 1.5 million, and the polyacrylate as a dispersing agent. The number average molecular weight is 50,000 or less.

According to the polymer composite film of the present disclosure, the kind of the surface treatment agent in the ceramic layer is not particularly limited, and may be selected from 3-glycidylpropyltrimethoxysilane and/or 3-glycidylpropyltriethoxylate. The silane, which further improves the interaction between the ceramic particles and the binder, and enhances the strength of the ceramic separator.

According to the polymer composite film of the present disclosure, in an embodiment, the thickness of the polymer base film in the ceramic separator is 5 to 30 μm, alternatively 6 to 25 μm. Further, the single-layer thickness of the ceramic layer may be selected from 1 to 5 μm, alternatively from 2 to 3.5 μm, which is more advantageous for improvement of high-temperature heat shrinkage resistance of the ceramic separator and improvement of gas permeability.

According to the polymer composite film of the present disclosure, in the embodiment, the ceramic layer in the ceramic separator may be formed on one side surface of the polymer base film, and also formed on both side surfaces of the polymer base film. In an embodiment, the ceramic layer is formed on both sides of the polymer base film.

According to the polymer composite film of the present disclosure, in an embodiment, the polymer composite film further includes a bonding layer formed at least on an outermost layer of one side surface of the polymer composite film, Optionally, the bonding layer is formed on an outermost layer on both side surfaces of the polymer composite film; the formation of the bonding layer can improve the viscosity between the polymer composite film and the positive and negative electrodes, and increase the polymer composite film. Set stability and improve battery safety. Optionally, in the present disclosure, the bonding layer contains an acrylate crosslinked polymer and a styrene-acrylate crosslinked copolymer and/or a vinylidene fluoride-hexafluoropropylene copolymer, and the bonding layer The porosity is 40 to 65%. When the ceramic separator further includes the above specific adhesive layer, it not only has good heat-resistant heat shrinkage, but also has higher bond strength and ionic conductivity.

"The first adhesive layer contains an acrylate crosslinked polymer and a styrene-acrylate crosslinked copolymer and/or a vinylidene fluoride-hexafluoropropylene copolymer" means that the adhesive layer contains an acrylate Crosslinked polymer and styrene-acrylate crosslinked copolymer without containing a vinylidene fluoride-hexafluoropropylene copolymer, or containing an acrylate crosslinked polymer and a vinylidene fluoride-hexafluoropropylene copolymer without The styrene-acrylate crosslinked copolymer is contained, or both the acrylate crosslinked polymer and the styrene-acrylate crosslinked copolymer and the vinylidene fluoride-hexafluoropropylene copolymer are contained. Further, "copolymer emulsion containing self-crosslinking type pure acrylic emulsion and self-crosslinking type styrene-acrylic emulsion and/or vinylidene fluoride and hexafluoropropylene" can also be similarly explained.

According to the polymer composite film of the present disclosure, the acrylate-based crosslinked polymer refers to a polymer obtained by crosslinking polymerization of a reactive acrylate monomer. The acrylate crosslinked polymer may have a degree of crosslinking of from 2 to 30%, alternatively from 5 to 20%. In the present disclosure, the degree of crosslinking refers to the percentage of the weight of the crosslinked polymer to the total weight of the polymer. Further, the acrylate-based crosslinked polymer may have a glass transition temperature of -20 ° C to 60 ° C, and optionally -12 ° C to 54 ° C. According to an embodiment of the present disclosure, the acrylate crosslinked polymer is a first acrylate crosslinked polymer and a second propylene a mixture of a olefin-based cross-linking polymer and/or a third acrylate-based cross-linked polymer, or a second acrylate-based cross-linked polymer, or a third acrylate-based cross-linked polymer; The first acrylate-based crosslinked polymer contains 70 to 80% by weight of a polymethyl methacrylate segment, 2 to 10% by weight of a polyethyl acrylate segment, and 10 to 20% by weight of a polybutyl acrylate chain. a segment and 2 to 10% by weight of a polyacrylic acid segment, the second acrylate-based crosslinked polymer containing 30 to 40% by weight of a polymethyl methacrylate segment and 2 to 10% by weight of polyethyl acrylate a segment, 50 to 60% by weight of a polybutyl acrylate segment and 2 to 10% by weight of a polyacrylic acid segment, the third acrylate-based crosslinked polymer containing 50 to 80% by weight of polymethacrylic acid An ester segment, 2 to 10% by weight of a polyethyl acrylate segment, 15 to 40% by weight of a polybutyl acrylate segment, and 2 to 10% by weight of a polyacrylic acid segment; the first acrylate crosslink The glass transition temperature of the polymer is from 50 ° C to 60 ° C, and the second acrylate cross-linking polymerization A glass transition temperature of -20 ℃ to -5 ℃, the third acrylic crosslinked polymer has a glass transition temperature of 30 ℃ to 50 ℃.

According to the polymer composite film of the present disclosure, the styrene-acrylate crosslinked copolymer means a copolymer obtained by copolymerization of a styrene monomer and a reactive acrylate monomer. The weight ratio of the styrene structural unit to the acrylate structural unit in the styrene-acrylate crosslinked copolymer may be from 0.5 to 2:1, alternatively from 0.67 to 1.5:1. The styrene-acrylate crosslinked copolymer may have a degree of crosslinking of from 2 to 30%, alternatively from 5 to 20%. Further, the styrene-acrylate crosslinked copolymer may have a glass transition temperature of from -30 ° C to 50 ° C, alternatively from -20 ° C to 50 ° C. According to an embodiment of the present disclosure, the styrene-acrylate crosslinked copolymer contains 40 to 50% by weight of a polystyrene segment, 5 to 15% by weight of a polymethyl methacrylate segment, 2 to 10 % by weight of polyethyl acrylate segment, 30 to 40% by weight of polybutyl acrylate segment and 2 to 10% by weight of polyacrylic acid segment; glass transition of the styrene-acrylate crosslinked copolymer The temperature is 15 to 30 °C.

According to the polymer composite film of the present disclosure, the vinylidene fluoride-hexafluoropropylene copolymer may have a glass transition temperature of -65 ° C to -40 ° C, optionally -60 ° C to -40 ° C. According to an embodiment of the present disclosure, the vinylidene fluoride-hexafluoropropylene copolymer contains 80 to 98% by weight of a polyvinylidene fluoride segment and 2 to 20% by weight of a polyhexafluoropropylene segment, optionally containing 90 to 96% by weight of a polyvinylidene fluoride segment and 4 to 10% by weight of a polyhexafluoropropylene segment; the vinylidene fluoride-hexafluoropropylene copolymer has a glass transition temperature of from -60 ° C to -40 ° C.

According to the polymer composite film of the present disclosure, in an embodiment, the adhesive layer contains an acrylate crosslinked polymer and a styrene-acrylate crosslinked copolymer and does not contain a vinylidene fluoride-hexafluoropropylene copolymer The weight ratio of the acrylate crosslinked polymer to the styrene-acrylate crosslinked copolymer is 1:0.05 to 2, optionally 1:1 to 2; or the bonding layer contains an acrylate a crosslinked polymer and a vinylidene fluoride-hexafluoropropylene copolymer and no styrene-acrylate crosslinked copolymer, the weight of the acrylate crosslinked polymer and the vinylidene fluoride-hexafluoropropylene copolymer The ratio is 1:0.3 to 25, optionally 1:0.4 to 19; or the bonding layer contains an acrylate crosslinked polymer, a styrene-acrylate crosslinked copolymer, and a vinylidene fluoride-hexafluorocarbon Propylene copolymer, the acrylate crosslinked polymer, styrene-acrylic acid The weight ratio of the ester crosslinked copolymer to the vinylidene fluoride-hexafluoropropylene copolymer is from 1:0.01 to 2:0.3 to 5, alternatively from 1:0.05 to 1.5:0.45 to 3. The inventors of the present disclosure have found through intensive studies that when the above polymers are used in combination in the above specific ratios, it is very advantageous for the improvement of the liquid absorption rate and electrical conductivity of the polymer composite film and the improvement of workability.

According to the polymer composite film of the present disclosure, in an embodiment, the adhesive layer contains a first acrylate-based crosslinked polymer, a second acrylate-based cross-linked polymer, and a styrene-acrylate cross-linked copolymer. And not containing a vinylidene fluoride-hexafluoropropylene copolymer, and the weight ratio of the first acrylate crosslinked polymer, the second acrylate crosslinked polymer and the styrene-acrylate crosslinked copolymer is 5 to 10:1:10 to 13; or,

The adhesive layer contains a first acrylate-based crosslinked polymer, a second acrylate-based cross-linked polymer, and a vinylidene fluoride-hexafluoropropylene copolymer, and does not contain a styrene-acrylate cross-linked copolymer. The weight ratio of the first acrylate-based crosslinked polymer, the second acrylate-based cross-linked polymer to the vinylidene fluoride-hexafluoropropylene copolymer is from 5 to 15:1:5 to 12; or

The adhesive layer contains a second acrylate crosslinked polymer and a vinylidene fluoride-hexafluoropropylene copolymer and does not contain a styrene-acrylate crosslinked copolymer, and the second acrylate crosslinked polymer The weight ratio of the copolymer of vinylidene fluoride to hexafluoropropylene is 1:5 to 20; or

The adhesive layer comprises a second acrylate crosslinked polymer, a styrene-acrylate crosslinked copolymer and a vinylidene fluoride-hexafluoropropylene copolymer, the second acrylate crosslinked polymer, benzene The weight ratio of the ethylene-acrylate crosslinked copolymer to the vinylidene fluoride-hexafluoropropylene copolymer is from 1:0.5 to 2:1 to 5; or

The adhesive layer contains a third acrylate crosslinked polymer, a styrene-acrylate crosslinked copolymer, and a vinylidene fluoride-hexafluoropropylene copolymer, the third acrylate crosslinked polymer, benzene The weight ratio of the ethylene-acrylate crosslinked copolymer to the vinylidene fluoride-hexafluoropropylene copolymer is from 1:0.5 to 2:1 to 5; or

The adhesive layer comprises a first acrylate crosslinked polymer, a second acrylate crosslinked polymer, a styrene-acrylate crosslinked copolymer, and a vinylidene fluoride-hexafluoropropylene copolymer, the first acrylic acid The weight ratio of the ester crosslinked polymer, the second acrylate crosslinked polymer, the styrene-acrylate crosslinked copolymer to the vinylidene fluoride-hexafluoropropylene copolymer is from 10 to 15:1:0.5 to 2 : 5 to 10;

Wherein the first acrylate-based crosslinked polymer contains 70 to 80% by weight of polymethyl methacrylate segments, 2 to 10% by weight of polyethyl acrylate segments, and 10 to 20% by weight of polyacrylic acid. a butyl ester segment and 2 to 10% by weight of a polyacrylic acid segment, the second acrylate-based crosslinked polymer containing 30 to 40% by weight of a polymethyl methacrylate segment, 2 to 10% by weight of a poly An ethyl acrylate segment, 50 to 60% by weight of a polybutyl acrylate segment and 2 to 10% by weight of a polyacrylic acid segment, the third acrylate crosslinked polymer containing 50 to 80% by weight of polymethyl Methyl methacrylate segment, 2 to 10% by weight of polyethyl acrylate segment, 15 to 40% by weight of polybutyl acrylate segment and 2 to 10 % by weight of polyacrylic acid segment, the styrene-acrylate crosslinked copolymer contains 40 to 50% by weight of polystyrene segments, 5 to 15% by weight of polymethyl methacrylate segments, 2 to 10% by weight of polyethyl acrylate segment, 30 to 40% by weight of polybutyl acrylate segment and 2 to 10% by weight of polyacrylic acid segment, the vinylidene fluoride-hexafluoropropylene copolymer contains 80 to 98 a wt% polyvinylidene fluoride segment and 2 to 20% by weight of a polyhexafluoropropylene segment; the first acrylate crosslinked polymer has a glass transition temperature of 50 ° C to 60 ° C, the second The acrylate-based crosslinked polymer has a glass transition temperature of -20 ° C to -5 ° C, and the third acrylate-based crosslinked polymer has a glass transition temperature of 30 ° C to 50 ° C, the styrene-acrylic acid The ester crosslinked copolymer has a glass transition temperature of 15 to 30 ° C, and the vinylidene fluoride-hexafluoropropylene copolymer has a glass transition temperature of -60 ° C to -40 ° C.

According to the polymer composite film of the present disclosure, in the embodiment, the adhesive layer further contains at least one of an acrylonitrile-acrylate copolymer, a chloropropane copolymer, and a styrene-butadiene copolymer. When the adhesive layer further contains an acrylonitrile-acrylate copolymer, it is advantageous to increase the ionic conductivity of the polymer composite film inside the battery; when the adhesive layer further contains a chloropropene copolymer and/or a butyl group When the benzene copolymer is used, it is advantageous to reduce the liquid absorption rate of the polymer composite film, so that the liquid absorption rate is not too high, because the liquid absorption rate is too high, so that the positive electrode and the negative electrode inside the battery lack electrolyte and crack the battery performance.

When the adhesive layer further contains an acrylonitrile-acrylate copolymer, the weight ratio of the acrylonitrile-acrylate copolymer to the acrylate crosslinked polymer may be 0.05 to 2:1, optionally 0.08 to 1.85:1. When the tie layer further contains a chloropropene copolymer, the weight ratio of the chloropropane copolymer to the acrylate crosslinked polymer may be from 0.15 to 7:1, alternatively from 0.2 to 6:1. When the tie layer further contains a styrene-butadiene copolymer, the weight ratio of the styrene-butadiene copolymer to the acrylate-based cross-linking polymer may be selected from 0.05 to 2:1, alternatively from 0.08 to 1.85:1.

Further, the single layer density of the bonding layer may be selected from 0.05 to 0.9 mg/cm ² , alternatively from 0.1 to 0.6 mg/cm ² . The one-sided thickness of the bonding layer may be selected from 0.1 to 1 μm, alternatively from 0.2 to 0.6 μm.

Meanwhile, the present disclosure also provides a method for preparing a polymer composite film, the preparation method comprising the steps of: S1, providing a porous base film; S2, preparing a spinning comprising the first polymer material and the second polymer material a silk solution, the spinning solution is formed by electrospinning on at least one side surface of the porous base film to form a heat resistant fiber layer; the first polymer material is a heat resistant polymer material having a melting point of 180 ° C or higher; The second polymer material has a melting point lower than the first polymer material, and the second polymer material has a liquid absorption rate of 40% or more in an electrolytic solution at 25° C., and the error is ±5%.

Optionally, the first polymer material has a liquid absorption rate of less than 5% in an electrolyte at 25 ° C, and an error of ± 5%;

Optionally, the first polymer material has a glass transition temperature of 100 ° C or higher;

Optionally, the second polymer material has a melting point of 100 to 150 ° C; optionally, the second polymer material has a glass transition temperature of 25 ° C or less;

Optionally, the second polymer material has a liquid absorption rate of 40-100% at 25 ° C, and the error is ± 5%;

Optionally, in the spinning polymer, the weight ratio of the first polymer material to the second polymer material is 0.5 to 10:1, Available from 1 to 5:1, optionally from 1 to 3:1.

According to the preparation method of the present disclosure, the above step S2 may further adopt a method of preparing a spinning solution containing the first polymer material and the second polymer material, and forming the resistance by electrospinning on the substrate by using the spinning solution. The heat fiber layer is further laminated on the at least one side surface of the porous base film.

According to the preparation method of the present disclosure, the above step S2 may take the following steps: S201, separately preparing a spinning solution A containing a first polymer material and a spinning solution B containing a second polymer material; S202; The spinning solution A and the spinning solution B were simultaneously subjected to electrospinning. At this time, the formed heat resistant fiber layer contains both the first polymer material and the second polymer material.

According to the preparation method of the polymer composite film, the above step S2 may also take the following steps: S211, blending the first polymer material and the second polymer material (optional blending conditions include: at normal temperature, rotation speed) Blending 2-6 h) at 300-2000 rpm to form a blend; reconstituting a spinning solution containing the blend; S212, electrospinning using the spinning solution to form a heat resistant fiber layer The fiber material in the heat resistant fiber layer is the heat resistant fiber layer material being a blend of the first polymer material and the second polymer material.

According to the preparation method of the present disclosure, in an embodiment, the weight ratio of the first polymer material to the second polymer material is from 0.5 to 10:1, alternatively from 1 to 5:1, particularly optionally from 1 to 3. : 1 blended. After the first polymer material and the second polymer material are blended to form a mixture, the method for preparing the spinning solution for spinning has the effect of forming a fibrous network structure, which is favorable for improving the thermal stability of the polymer composite film.

According to the preparation method of the present disclosure, the first polymer material and the second polymer material in the spinning solution are dissolved by a solvent to facilitate the subsequent electrospinning process. In the present disclosure, the solvent is selected from one or more of acetone, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, toluene, and the like.

According to the production method of the present disclosure, the spinning solution (including the spinning solution A, the spinning solution B, and a spinning solution containing the first polymer material and the second polymer material blend) is used for A heat resistant fiber layer was prepared by an electrospinning method in a subsequent step. Therefore, in the spinning solution, the concentration range of the spinning polymer (including the first polymer material and/or the second polymer material) is a concentration range in which spinning can be performed by an electrospinning method. In an embodiment, in the present disclosure, in the spinning solution, the spinning solution has a concentration of the spinning polymer of 3 to 30% by weight. It can be selected from 8 to 20% by weight. When the relative molecular mass of the spinning polymer is fixed, the concentration of the spinning solution is a decisive factor affecting the entanglement of the molecular chain in the solution under certain other conditions. The polymer solution can be divided into three types: polymer dilute solution, sub-concentrated solution and concentrated solution according to the difference in concentration and molecular chain morphology. In the dilute solution, the molecular chains are separated from each other and the distribution is uniform. As the concentration of the solution increases, the molecular chains interpenetrate and entangle. The boundary concentration of the dilute solution and the sub-concentrated solution is called the contact concentration, and refers to the concentration at which the molecular chain contacts as the concentration of the solution increases, and then overlaps. The boundary concentration of the concentrated solution and the concentrated solution is called the entanglement concentration, which means that as the concentration of the solution further increases, the molecular chains interpenetrate and intertwined. The concentration of the knot. In the present disclosure, when the spinning solution concentration is within the above range, the yarn forming performance can be effectively ensured. Moreover, as the concentration of the spinning solution increases, the degree of entanglement of the polymer increases, and the filament formation property is better. In the present disclosure, when electrospinning is carried out using a spinning solution containing different polymers, the concentration of each spinning solution is independently selected from the above concentration ranges.

According to the preparation method of the present disclosure, the method of preparing the heat resistant fiber layer in the step S3 is electrospinning, and the basic principle of the electrospinning is well known to those skilled in the art, specifically, applying a voltage between the spraying device and the receiving device. A jet is formed from the spinning solution originating from the end of the cone of the spraying device and is stretched in the electric field to finally form fibers on the receiving device. Wherein the receiving device comprises a drum (rotatable) or a receiving plate. The electrospinning method generally includes a needle spinning method and a needleless spinning method, and specific processes are well known to those skilled in the art and will not be described herein.

When the electrospinning method is a needle spinning method, the flow rate of the spinning solution may be selected from 0.3 to 5 mL/h, optionally from 0.6 to 2 mL/h; and the spinning temperature may be selected from 25 to 70 ° C. It is selected to be 30 to 50 ° C; the spinning humidity can be selected from 2% to 60%, optionally from 2% to 50%; the spinning voltage can be selected from 5 to 25 kV, optionally from 8 to 20 kV. When the flow rate is within the above-mentioned optional range, it is ensured that a suitable fiber diameter is obtained, and at the same time, the needle can be effectively prevented from being occluded, and the spinning can be smoothly performed. Particularly in the case of using the mixed solvent provided by the present disclosure, the flow rate within the above range can be controlled to obtain a heat resistant fiber layer having excellent porosity and adhesive properties. When the spinning temperature and the humidity are within the above range, the mixture is mixed with the above-mentioned mixed solvent to ensure that the fibers obtained by the spinning are smoothly dried after being formed into a filament, avoiding the adhesion of the fibers, resulting in a decrease in porosity, and avoiding sticking of the heat-resistant fiber layer. The performance of the junction is degraded. When the voltage is within the above range, the spinning solution can be effectively excited to form a jet, thereby generating an effective stretching effect in the electric field, obtaining a fiber of a suitable diameter, ensuring the shape of the formed fiber, and improving the porosity of the heat-resistant fiber layer. And bonding properties. Further, the receiving device may be selected as a drum, and the rotation speed of the drum may be selected from 100 to 6000 rpm, alternatively from 1000 to 2000 rpm. When the linear velocity of the surface of the collecting device for collecting fibers is too small, since the rapidly moving jet is in a chaotic state, the fibers formed at this time are distributed in a state of irregular accumulation on the surface of the collecting device, and the obtained heat resistant fiber layer is obtained. The mechanical strength is poor. When the surface speed of the collecting device reaches a certain degree, the formed fibers are tightly attached to the surface of the collecting device in a circumferential manner, the fibers are deposited in the same direction, and are substantially in a straight state, that is, a fiber bundle which is straight and extends in the same direction. . On the other hand, when the surface speed of the surface of the collecting device is too large, the fiber jet is broken due to the excessively fast receiving speed, and continuous fibers cannot be obtained. Through continuous testing of the conventional electrospinning process, the inventors have found that when the speed of the collecting device is from 100 to 6000 rpm, a fiber bundle having straight straight direction extension can be obtained. In the embodiment, when the rotation speed of the collecting device is 1000 to 2000 rpm, the shape of the fiber in the obtained heat resistant fiber layer is better, and the mechanical strength of the heat resistant fiber layer is more favorable.

When the electrospinning method is a needleless spinning method, the spinning conditions may include: a temperature of 25 to 70 ° C, a humidity of 2% to 60%, and a liquid pool moving speed of 0 to 2000 mm/sec. The moving speed of the material is 0 to 20000 mm/min (the collecting device is plate-shaped, not rotated at this time) or the rotating speed of the drum is 100 to 6000 rpm (the collecting device is a roller at this time), and the positive electrode voltage (the voltage at the source end of the fiber) is 0 to 150 kV. The negative voltage (voltage of the collecting device) is -50 to 0 kV, The voltage difference (the voltage difference between the source end and the collecting device) is 10 to 100 kV; the optional includes: the temperature is 30 to 50 ° C, the humidity is 2% to 50%, and the liquid pool moving speed is 100 to 400 mm/sec. The material moving speed is 1000 to 15000 mm/min or the drum rotation speed is 1000 to 2000 rpm, the positive electrode voltage is 10 to 40 kV, the negative electrode voltage is -30 to 0 kV, and the voltage difference is 20 to 60 kV.

The inventors of the present disclosure have found through a large number of experiments that under the premise of the above-mentioned optional range, the concentration of the spinning polymer in the spinning solution can achieve a good solvent volatilization rate and fiber formation speed by the electrospinning process of the above conditions. Matching, it is possible to obtain a heat-resistant fiber layer with better morphology, higher adhesion, better adhesion between silk and silk in the heat-resistant fiber layer, and a porosity of 70% or more, optionally 70 to 95%, for example 75 to 95%.

The present disclosure is not particularly limited to the fiber diameter and thickness in the heat resistant fiber layer, and may be specifically modified by controlling specific process conditions. Alternatively, the fiber has an average diameter of 100 to 2000 nm, and the heat resistant fiber. The layer has a single side thickness of 0.5 to 30 μm; the heat resistant fiber layer has an areal density of 0.2 to 15 g/m ² , optionally 3 to 6 g/m ² ; and the heat resistant fiber layer has a porosity of 75 to 95 %.

According to the method for producing a polymer composite film provided by the present disclosure, the heat resistant fiber layer formed by the above electrospinning may be composited on one side surface of the porous base film or simultaneously laminated on both sides of the porous base film. On the surface. In an embodiment, in step S3, the heat resistant fiber layer is formed on both sides of the porous base film by electrospinning, and is selectively subjected to hot rolling and drying, and then to the porous base film. The other side is compositely formed into a heat resistant fiber layer, and optionally subjected to hot rolling and drying.

According to the present disclosure, after the heat-resistant fiber layer is formed on the porous base film by electrospinning in the step S3, or after the heat-resistant fiber layer is composited onto the porous base film, the method further includes The film is subjected to a film pressing treatment at 50 to 120 ° C and 0.5 to 15 MPa, for example, hot rolling (hot rolling conditions: temperature: 50 to 60 ° C, pressure: 1 to 15 MPa), followed by blast drying at 50 ° C for 24 hours.

According to the preparation method of the present disclosure, the porous base film in the step S1 is a ceramic separator including a polymer base film and a ceramic layer on at least one side surface of the polymer base film; in the step S2 A heat resistant fiber layer is formed on the surface of the ceramic layer in the ceramic separator. According to the present disclosure, by using a ceramic separator, the ceramic layer of the ceramic separator is characterized by the inorganic particle layer, so that the heat-resistant fiber layer can be more firmly bonded to the surface of the ceramic layer, and the prepared polymer can be effectively improved on the one hand. The peel strength of the composite film, on the other hand, the inorganic particle layer is located between the separator and the heat resistant fiber layer, and can impart excellent heat shrinkage resistance to the polymer composite film as a whole.

According to the preparation method of the present disclosure, the preparation method of the ceramic separator in the step S1 comprises: S11, providing a polymer base film; S12, adding ceramic particles, a binder, a dispersing agent and a thickening agent according to a weight ratio of 100: (2) To 8): (0.3 to 1): a ratio of (0.5 to 1.8) is stirred and mixed to obtain a ceramic layer slurry, and the ceramic layer slurry is applied to at least one side surface of the polymer base film, and dried. Obtaining a ceramic layer (optionally forming a ceramic layer on both side surfaces of the polymer base film); The number average molecular weight of the dispersant is 50,000 or less.

According to the preparation method of the present disclosure, considering the dispersibility of each raw material in the slurry of the ceramic layer and the stability of the slurry of the ceramic layer, in the step S12, the ceramic particles, the binder, the dispersing agent and the thickener are selected in 3000. Up to 10,000 rpm, optionally 3000 to 9000 rpm, and particularly optionally 3000 to 8000 rpm. When the materials forming the ceramic layer slurry are mixed at the above optional rotation speed, it is more advantageous to increase the surface density of the ceramic separator.

According to the preparation method of the present disclosure, ceramic particles, a binder, a dispersing agent and a thickener may be optionally mixed in the above weight ratio, when the amount of the dispersing agent is less than 0.3 parts by weight and/or the amount of the thickener is low. to 0.5 parts by weight, the ceramic slurry may result in insufficient dispersibility, it is difficult to form a close-packed so as to obtain a high ^{2 <ρ≤2.7mg} / cm areal density of the present disclosure 1.8mg / cm ^2; and when a high amount of the dispersing agent When the amount of the component is more than 1.8 parts by weight based on 1 part by weight and/or the thickener, the gas permeability of the separator may be affected to affect the battery output characteristics. When the amount of the binder is less than 2 parts by weight, the bond strength may be insufficient; when the amount of the binder is more than 8 parts by weight, the gas permeability of the ceramic separator may be affected. When the number average molecular weight of the dispersant is higher than 50,000, the dispersion effect of the ceramic slurry may be affected, and the areal density may be lowered. When the stirring speed is below 3000 rpm for, insufficient dispersion slurry may be formed to obtain a high bulk density 1.8mg / cm ² <ρ≤2.7mg / cm ² surface density; when the stirring speed is higher than 10000rpm It may damage the stability of the ceramic layer slurry.

According to the production method of the present disclosure, the thickness of the polymer base film may be generally from 5 to 30 μm, alternatively from 6 to 25 μm. The material of the polymer base film has been described above and will not be described herein. In addition, the ceramic layer slurry may be used in an amount such that the single-layer thickness of the ceramic layer is 1-5 μm, and optionally 2-3.5 μm, which is more favorable for the improvement of the high-temperature heat shrinkage resistance of the ceramic separator and the gas permeability. Improvement. The types and properties of the ceramic particles, binder, dispersant and thickener in the ceramic layer slurry and the material of the polymer base film have been described above and will not be described herein.

Optionally, in the step S12, the ceramic particles, the binder, the dispersing agent and the thickener are stirred and mixed according to a weight ratio of 100:(4 to 6):(0.4 to 0.8):(0.7 to 15). . When the amount of each substance in the ceramic layer slurry is controlled within the above optional range, the obtained ceramic separator can have a higher areal density and better high temperature heat shrinkage resistance.

In addition, according to the preparation method of the polymer composite film of the present disclosure, in the embodiment, the ceramic layer slurry obtained by mixing in the step S12 may further contain a surface treatment agent, and the surface treatment agent is 3-glycidyloxy group. Propyltrimethoxysilane and/or 3-glycidoxypropyltriethoxysilane can further improve the interaction between the ceramic particles and the binder and enhance the strength of the ceramic separator. Further, the surface treatment agent may be used in an amount of 1.5 parts by weight or less, alternatively 0.5 to 1.2 parts by weight, based on 100 parts by weight of the ceramic particles, which is more advantageous for the improvement of the gas permeability of the ceramic separator.

In addition, the ceramic layer slurry may further contain a surfactant such as sodium dodecylbenzenesulfonate, and the like. The amount of the agent can be a conventional choice in the art, and those skilled in the art will be aware of this and will not be described herein.

According to the preparation method of the present disclosure, in the embodiment, the step S12 comprises stirring the ceramic particles, the dispersant and the thickener at a high speed of 3000 to 10000 rpm for 0.5 to 3 hours, adding a surface treatment agent and continuing to stir 0.5. Up to 3 hours, then adding a binder and stirring at 3000 to 4000 rpm for 0.5 to 2 hours, then applying the obtained slurry to at least one side surface of the polymer base film, and then drying to a ceramic layer is formed on at least one side surface of the polymer base film; wherein the ceramic particles, the binder, the dispersant, and the thickener are in a weight ratio of 100: (2 to 8): (0.3 to 1): (0.5 to 1.8) The ratio is charged, and the number average molecular weight of the dispersant is 50,000 or less. Wherein, the drying temperature is 50 to 80 °C. Optionally, the ceramic layer is formed on both surfaces of the polymer base film in the step S12.

According to the production method of the present disclosure, further comprising the step S3 of forming a bonding layer on at least one side surface of the composite film obtained by the step S2 (the bonding layer is formed on at least one side of the polymer composite film Outer layer). For the method of forming the bonding layer, reference may be made to the conventional technical means in the art, and details are not described herein again.

In the present disclosure, optionally, the above step S3 comprises attaching a bonding layer slurry containing a self-crosslinking type pure acrylic emulsion and a self-crosslinking type styrene-acrylic emulsion, and/or a copolymerized emulsion of vinylidene fluoride and hexafluoropropylene. On the outermost side of at least one side surface of the composite film obtained in the step S2, drying is then carried out to form a bonding layer having a porosity of 40 to 65%. At this time, the ceramic separator not only has good high temperature heat shrinkage resistance, but also has higher ionic conductivity and bonding strength, and has more industrial application prospects.

The self-crosslinking type pure acrylic emulsion refers to an emulsion obtained by emulsion polymerization of a reactive acrylate monomer. The degree of crosslinking of the acrylate-based crosslinked polymer in the self-crosslinking type pure acrylic emulsion may be 2 to 30%, alternatively 5 to 20%. Further, the glass transition temperature of the acrylate-based crosslinked polymer in the self-crosslinking type pure acrylic emulsion may be selected from -20 ° C to 60 ° C, and optionally from -12 ° C to 54 ° C. According to an embodiment of the present disclosure, the self-crosslinking type pure acrylic emulsion is a mixture of a first self-crosslinking type pure acrylic emulsion and a second self-crosslinking type pure acrylic emulsion and/or a third self-crosslinking type pure acrylic emulsion. Or a second self-crosslinking type pure acrylic emulsion, or a third self-crosslinking type pure acrylic emulsion; the acrylate crosslinked polymer in the first self-crosslinking type pure acrylic emulsion contains 70 to 80 weights % polymethyl methacrylate segment, 2 to 10% by weight of polyethyl acrylate segment, 10 to 20% by weight of polybutyl acrylate segment and 2 to 10% by weight of polyacrylic acid segment, The acrylate crosslinked polymer in the second self-crosslinking type pure acrylic emulsion contains 30 to 40% by weight of polymethyl methacrylate segments, 2 to 10% by weight of polyethyl acrylate segments, 50 to 60 5% by weight of polybutyl acrylate segment and 2-10% by weight of polyacrylic acid segment, the acrylate crosslinked polymer in the third self-crosslinking pure acrylic emulsion contains 50 to 80% by weight of polymethyl Methyl acrylate segment, 2 to 10% by weight of polyethyl acrylate segment, 15 to 40% by weight of polybutyl acrylate segment and 2 10% by weight of a polyacrylic acid segment; the acrylate-based crosslinked polymer in the first self-crosslinking type pure acrylic emulsion has a glass transition temperature of 50 ° C to 60 ° C, and the second self-crosslinking type is pure Acrylate crosslinked polymer in acrylic emulsion The glass transition temperature is -20 ° C to -5 ° C, and the glass transition temperature of the acrylate crosslinked polymer in the third self-crosslinking type pure acrylic emulsion is from 30 ° C to 50 ° C.

The self-crosslinking type styrene-acrylic emulsion refers to a copolymer emulsion obtained by copolymerizing a styrene monomer and a reactive acrylate monomer. Wherein, the weight ratio of the styrene structural unit to the acrylate structural unit in the styrene-acrylate copolymer may be from 0.5 to 2:1, and optionally from 0.67 to 1.5:1. The styrene-acrylate crosslinked copolymer in the self-crosslinking styrene-acrylic emulsion may have a degree of crosslinking of 2 to 30%, alternatively 5 to 20%. Further, the glass transition temperature of the styrene-acrylate crosslinked copolymer in the self-crosslinking type styrene-acrylic emulsion may be selected from -30 ° C to 50 ° C, alternatively from -20 ° C to 50 ° C. In an embodiment, the styrene-acrylate crosslinked copolymer in the self-crosslinking styrene-acrylic emulsion contains 40 to 50% by weight of polystyrene segments, and 5 to 15% by weight of polymethacrylic acid. An ester segment, 2 to 10% by weight of a polyethyl acrylate segment, 30 to 40% by weight of a polybutyl acrylate segment, and 2 to 10% by weight of a polyacrylic acid segment; the styrene-acrylate cross The co-copolymer has a glass transition temperature of 15 to 30 °C.

The glass transition temperature of the vinylidene fluoride-hexafluoropropylene copolymer in the copolymer emulsion of vinylidene fluoride and hexafluoropropylene may be selected from -65 ° C to -40 ° C, and optionally from -60 ° C to -40 ° C. According to an embodiment of the present disclosure, the vinylidene fluoride-hexafluoropropylene copolymer in the copolymer emulsion of vinylidene fluoride and hexafluoropropylene contains 80 to 98% by weight of a polyvinylidene fluoride segment and 2 to 20% by weight a polyhexafluoropropylene segment optionally comprising 90 to 96% by weight of a polyvinylidene fluoride segment and 4 to 10% by weight of a polyhexafluoropropylene segment; vitrification of the vinylidene fluoride-hexafluoropropylene copolymer The transition temperature can be selected from -60 ° C to -40 ° C.

The copolymer emulsion of vinylidene fluoride and hexafluoropropylene can be obtained commercially, or can be obtained by various existing methods, or can be obtained by disposing a vinylidene fluoride-hexafluoropropylene copolymer powder into an emulsion. According to a specific embodiment of the present disclosure, the copolymer emulsion of vinylidene fluoride and hexafluoropropylene is prepared by the following method:

(1) dissolving the dispersing agent in water and selectively adjusting its pH value to obtain an aqueous solution A of the dispersing agent;

(2) The vinylidene fluoride-hexafluoropropylene copolymer powder is slowly added to the aqueous solution A of the dispersant under stirring, and after the addition of the vinylidene fluoride-hexafluoropropylene copolymer powder, the mixture is stirred at a low speed and then stirred at a high speed. Finally, the mixture is uniformly dispersed under high pressure to form a copolymer emulsion of vinylidene fluoride and hexafluoropropylene.

The dispersant is a water-soluble polymer dispersant, and includes both an ionic (polyelectrolyte) and a nonionic. Wherein, the ionic dispersing agent is a polycarboxylic acid type dispersing agent which is homopolymerized by a carboxyl group-containing vinyl monomer (such as acrylic acid, maleic anhydride, etc.) or copolymerized with other monomers, and then neutralized the alcohol ester with a base. Get it. Examples of the ionic dispersing agent include, but are not limited to, polyacrylic acid (PAA), polyethyleneimine (PEI), cetyltrimethylammonium bromide (CTAB), polyamide, polyacrylamide (PAM). , Acrylic-Acrylate Copolymer, Acrylic-Acrylamide Copolymer [P(AA/AM)], Ammonium Acrylate-Acrylate Copolymer, Styrene-Maleic Anhydride Copolymer (SMA), Styrene- Acrylic copolymer, acrylic acid-maleic anhydride copolymer, maleic anhydride-acrylamide copolymer, and the like. The nonionic dispersing agent includes polyethylene glycol (PEG), polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), fatty alcohol polyoxyethylene ether (JFC), and the like. Dispersing agent The weight average molecular weight is from 100 to 500 000 g/mol, optionally from 1000 to 100000 g/mol. The concentration of the aqueous solution A of the dispersant is from 0.01 to 10% by weight, alternatively from 0.05 to 5% by weight, alternatively from 0.1 to 2% by weight. The dispersant is used in an amount of from 0.05 to 10% by weight, alternatively from 0.1 to 6% by weight, alternatively from 0.1 to 2% by weight, based on the amount of the vinylidene fluoride-hexafluoropropylene copolymer powder used. When the ionic dispersant used is an anionic polymer (such as PAM), adjusting the solution to pH=8 to 9 can completely dissociate the anionic polymer, thereby reacting the vinylidene fluoride-hexafluoropropylene copolymer powder. Effectively protect and stabilize it in the aqueous phase. When the ionic dispersant used is a cationic polymer (such as PEI, CTAB), the solution is adjusted to pH = 4 to 5, so that the cationic polymer can be well dissociated, thus the vinylidene fluoride-hexafluorocarbon The propylene copolymer powder is effectively protected so that it is stably dispersed in the aqueous phase. When the dispersant used is a nonionic polymeric dispersant, the pH of the solution is not adjusted.

According to an embodiment of the present disclosure, the tie layer slurry contains a self-crosslinking type pure acrylic emulsion and a self-crosslinking type styrene-acrylic emulsion and does not contain a copolymerized emulsion of vinylidene fluoride and hexafluoropropylene, the self-crosslinking type. The weight ratio of the solid content of the pure acrylic emulsion to the self-crosslinking styrene-acrylic emulsion is 1:0.05 to 2, optionally 1:1 to 2; or the bonding layer slurry contains a self-crosslinking pure acrylic emulsion. a copolymerization emulsion with vinylidene fluoride and hexafluoropropylene and containing no self-crosslinking styrene-acrylic emulsion, the solid content ratio of the self-crosslinking pure acrylic emulsion to the copolymerized emulsion of vinylidene fluoride and hexafluoropropylene is 1 : 0.3 to 25, optionally 1:0.4 to 19; or, the tie layer slurry contains a self-crosslinking type pure acrylic emulsion, a self-crosslinking type styrene-acrylic emulsion, a copolymer emulsion of vinylidene fluoride and hexafluoropropylene The self-crosslinking type pure acrylic emulsion, the self-crosslinking type styrene-acrylic emulsion, the copolymerized emulsion of vinylidene fluoride and hexafluoropropylene have a solid content ratio of 1:0.01 to 2:0.3 to 5, optionally 1 : 0.05 to 1.5: 0.45 to 3. The inventors of the present disclosure have found through intensive studies that when the above polymer emulsions are used in combination with the above specific ratios, it is very advantageous for the improvement of the liquid absorption rate and electrical conductivity of the ceramic membrane and the improvement of the workability.

According to a particularly optional embodiment of the present disclosure, the tie layer slurry comprises a first self-crosslinking type pure acrylic emulsion, a second self-crosslinking type pure acrylic emulsion, and a self-crosslinking type styrene-acrylic emulsion, and The copolymerized emulsion containing vinylidene fluoride and hexafluoropropylene, the first self-crosslinking type pure acrylic emulsion, the second self-crosslinking type pure acrylic emulsion and the self-crosslinking type styrene-acrylic emulsion have a solid content ratio of 5 to 10: 1:10 to 13; or,

The adhesive layer slurry comprises a first self-crosslinking type pure acrylic emulsion, a second self-crosslinking type pure acrylic emulsion, and a copolymerized emulsion of vinylidene fluoride and hexafluoropropylene, and does not contain a self-crosslinking type styrene-acrylic emulsion. The weight ratio of the first self-crosslinking type pure acrylic emulsion, the second self-crosslinking type pure acrylic emulsion and the copolymerized emulsion of vinylidene fluoride and hexafluoropropylene is 5 to 15:1:5 to 12; or

The bonding layer slurry comprises a second self-crosslinking type pure acrylic emulsion and a copolymerized emulsion of vinylidene fluoride and hexafluoropropylene and does not contain a self-crosslinking type styrene-acrylic emulsion, and the second self-crosslinking type pure acrylic emulsion The weight ratio of the solid content of the copolymer emulsion of vinylidene fluoride and hexafluoropropylene is 1:5 to 20; or

The bonding layer slurry comprises a second self-crosslinking type pure acrylic emulsion, a self-crosslinking type styrene-acrylic emulsion, and a vinylidene fluoride and a hexafluorocarbon a copolymerization emulsion of propylene, the second self-crosslinking type pure acrylic emulsion, the self-crosslinking type styrene-acrylic emulsion and the copolymerized emulsion of vinylidene fluoride and hexafluoropropylene have a solid content ratio of 1:0.5 to 2:1 to 5; or,

The bonding layer slurry comprises a third self-crosslinking type pure acrylic emulsion, a self-crosslinking type styrene-acrylic emulsion, and a copolymerized emulsion of vinylidene fluoride and hexafluoropropylene, and the third self-crosslinking type pure acrylic emulsion, self The weight ratio of the crosslinked styrene-acrylic emulsion to the copolymerized emulsion of vinylidene fluoride and hexafluoropropylene is from 1:0.5 to 2:1 to 5; or

The bonding layer slurry comprises a first self-crosslinking type pure acrylic emulsion, a second self-crosslinking type pure acrylic emulsion, a self-crosslinking type styrene-acrylic emulsion, and a copolymer emulsion of vinylidene fluoride and hexafluoropropylene, The cross-linking type pure acrylic emulsion, the second self-crosslinking type pure acrylic emulsion, the self-crosslinking type styrene-acrylic emulsion and the copolymerized emulsion of vinylidene fluoride and hexafluoropropylene have a solid content ratio of 10 to 15:1:0.5 to 2:5 to 10;

The acrylate crosslinked polymer in the first self-crosslinking type pure acrylic emulsion contains 70 to 80% by weight of a polymethyl methacrylate segment, 2 to 10% by weight of a polyethyl acrylate segment, 10 Up to 20% by weight of the polybutyl acrylate segment and 2 to 10% by weight of the polyacrylic acid segment, and the acrylate crosslinked polymer in the second self-crosslinking type pure acrylic emulsion contains 30 to 40% by weight a polymethyl methacrylate segment, 2 to 10% by weight of a polyethyl acrylate segment, 50 to 60% by weight of a polybutyl acrylate segment, and 2 to 10% by weight of a polyacrylic acid segment, the third The acrylate crosslinked polymer in the self-crosslinking type pure acrylic emulsion contains 50 to 80% by weight of polymethyl methacrylate segments, 2 to 10% by weight of polyethyl acrylate segments, 15 to 40% by weight a polybutyl acrylate segment and 2 to 10% by weight of a polyacrylic acid segment, the styrene-acrylate crosslinked copolymer in the self-crosslinking styrene-acrylic emulsion containing 40 to 50% by weight of polystyrene Segment, 5 to 15% by weight of polymethyl methacrylate segment, 2 to 10% by weight of polyethyl acrylate segment, 30 Up to 40% by weight of the polybutyl acrylate segment and 2 to 10% by weight of the polyacrylic acid segment, the vinylidene fluoride-hexafluoropropylene copolymer in the copolymer emulsion of vinylidene fluoride and hexafluoropropylene contains 80 to 98 a wt% polyvinylidene fluoride segment and 2 to 20% by weight of a polyhexafluoropropylene segment; the acrylate crosslinked polymer in the first self-crosslinking type pure acrylic emulsion has a glass transition temperature of 50 The glass transition temperature of the acrylate crosslinked polymer in the second self-crosslinking type pure acrylic emulsion is from -20 ° C to -5 ° C from ° C to 60 ° C, and the third self-crosslinking type pure acrylic emulsion The acrylate-based crosslinked polymer has a glass transition temperature of 30 ° C to 50 ° C, and the styrene-acrylate cross-linked copolymer has a glass transition temperature of 15 to 30 ° C, and the vinylidene fluoride- The hexafluoropropylene copolymer has a glass transition temperature of from -60 ° C to -40 ° C.

According to the present disclosure, optionally, the tie layer slurry further contains at least one of a copolymer emulsion of acrylonitrile and acrylate, a chloropropene emulsion, and a styrene-butadiene latex. When the copolymer layer slurry further contains a copolymer emulsion of acrylonitrile and acrylate, it is advantageous to increase the ionic conductivity of the polymer composite film inside the battery; when the bonding layer slurry further contains a chloropropene emulsion And / or styrene-butadiene latex, it is beneficial to reduce the liquid absorption rate of the polymer composite membrane, so that the liquid absorption rate is not too high, because the liquid absorption rate is too high, the internal and negative electrodes of the battery lack electrolyte and crack the battery performance.

When the tie layer slurry further contains a copolymer emulsion of acrylonitrile and acrylate, the acrylonitrile and acrylate The weight ratio of the solid content of the copolymer emulsion to the solid content of the self-crosslinking type pure acrylic emulsion may be selected from 0.05 to 2:1, alternatively from 0.08 to 1.85:1. When the binder layer slurry further contains a chloropropene emulsion, the weight ratio of the solid content of the chloropropene emulsion to the solid content of the self-crosslinking type pure acrylic emulsion may be selected from 0.15 to 7:1, optionally 0.2 to 6:1. When the binder layer slurry further contains a styrene-butadiene latex, the weight ratio of the solid content of the styrene-butadiene latex to the solid content of the self-crosslinking type pure acrylic emulsion may be 0.05 to 2:1, optionally 0.08 to 1.85:1.

Further, in order to more favor the adhesion of the bonding layer slurry, the bonding layer slurry may optionally have a total solid content of 0.5 to 25% by weight, alternatively 1 to 20% by weight, for example, 1 Up to 10% by weight.

The method of attaching may alternatively adopt a spray coating method and/or a screen printing method to form a porous film having the above porosity directly by a discontinuous coating by a spray coating method and/or a screen printing method, so that a porous film can be prepared (not Continuous) self-crosslinking polymer coating without the need for a phase separation process.

The conditions of the spraying and screen printing of the present disclosure are not particularly limited. For example, the spray temperature can be selected from 30 to 80 ° C, optionally from 40 to 75 ° C. The screen printing temperature may be selected from 30 to 80 ° C, alternatively from 40 to 75 ° C.

The amount of the tie layer paste may be selected such that the formed tie layer has a single side thickness of 0.1 to 1 μm, alternatively 0.2 to 0.6 μm.

The temperature at which the adhesive layer slurry is dried in the present disclosure is not particularly limited and may be 30 to 80 ° C, and optionally 40 to 75 ° C.

The present disclosure also provides a ceramic separator prepared by the above method.

Further, the present disclosure also provides a lithium ion battery comprising a positive electrode sheet, a negative electrode sheet, an electrolyte, and a battery separator, wherein the battery separator is the above polymer composite membrane of the present disclosure.

The electrolyte is well known to those skilled in the art and typically consists of an electrolyte lithium salt and an organic solvent. Wherein the lithium salt of the electrolyte is a dissociable lithium salt, for example, at least one selected from the group consisting of lithium hexafluorophosphate (LiPF ₆ ), lithium perchlorate (LiClO ₄ ), lithium tetrafluoroborate (LiBF ₄ ), and the like, an organic solvent. It may be selected from the group consisting of ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), vinylene carbonate (VC), and the like. At least one of them. Optionally, the concentration of the lithium salt of the electrolyte in the electrolyte is 0.8 to 1.5 mol/L.

The positive electrode sheet is prepared by coating a positive electrode material for a lithium ion battery, a conductive agent, and a binder onto an aluminum foil. The positive electrode material used includes any positive electrode material usable for a lithium ion battery, for example, lithium cobalt oxide (LiCoO ₂ ), lithium nickel oxide (LiNiO ₂ ), lithium manganese oxide (LiMn ₂ O ₄ ), lithium iron phosphate (LiFePO _{4 ).} At least one of the others.

The negative electrode sheet is prepared by applying a negative electrode material for a lithium ion battery, a conductive agent, and a binder to a copper foil. The negative electrode material used includes any negative electrode material usable for a lithium ion battery, for example, at least one of graphite, soft carbon, hard carbon, and the like.

The main improvement of the lithium ion battery provided by the present disclosure is that a new polymer composite film is used as the battery. The separator is used, and the arrangement of the positive electrode sheet, the negative electrode sheet, the polymer composite film, and the electrolyte solution (connection method) can be the same as that of the prior art, and those skilled in the art can understand that it will not be described herein.

The lithium ion battery provided by the present disclosure has the advantages of good cycle performance, long service life, good rate charge and discharge performance, and high temperature performance.

The method for preparing a lithium ion battery provided by the present disclosure includes a positive electrode sheet, a battery separator and a negative electrode sheet which are sequentially laminated or wound into a polar core, and then an electrolyte is injected into the polar core and sealed, wherein the battery separator is the above polymerization. Compound membrane. The material or composition of the positive electrode sheet, the negative electrode sheet and the electrolyte solution has been described above, and will not be described herein.

The present disclosure will be described in detail below through specific embodiments.

In the following examples and comparative examples, the physical and chemical parameters of the raw materials are as follows:

(1) Composition of self-crosslinking type pure acrylic emulsion:

1.1) 1040: polybutyl acrylate segment accounts for 15% by weight, polymethyl methacrylate segment accounts for 75% by weight, polyethyl acrylate segment accounts for 5% by weight, polyacrylic acid segment accounts for 5% by weight, vitrification Transformation temperature Tg=54°C, solid content 50% by weight, Shanghai Aigao Chemical Co., Ltd.;

1.2) 1005: polybutyl acrylate segment accounted for 55 wt%, polymethyl methacrylate segment accounted for 35 wt%, polyethyl acrylate segment accounted for 5% by weight, polyacrylic acid segment accounted for 5% by weight, vitrification Transformation temperature Tg=-12°C, solid content 50% by weight, Shanghai Aigao Chemical Co., Ltd.;

1.3) 1020: polybutyl acrylate segment accounts for 25% by weight, polymethyl methacrylate segment accounts for 65% by weight, polyethyl acrylate segment accounts for 5% by weight, polyacrylic acid segment accounts for 5% by weight, vitrification The transformation temperature is Tg=40°C, and the solid content is 50% by weight. Shanghai Aigao Chemical Co., Ltd.

(2) Composition of self-crosslinking styrene-acrylic emulsion:

S601: polystyrene segment accounts for 45% by weight, polybutyl acrylate segment accounts for 35% by weight, polymethyl methacrylate segment accounts for 10% by weight, polyethyl acrylate segment accounts for 5% by weight, polyacrylic acid chain The segment accounts for 5% by weight, the glass transition temperature is Tg=22°C, and the solid content is 50% by weight. Shanghai Aigao Chemical Co., Ltd.

(3) Copolymerization emulsion of vinylidene fluoride and hexafluoropropylene:

10278: Polyvinylidene fluoride segment accounts for 95% by weight, polyhexafluoropropylene segment accounts for 5% by weight, weight average molecular weight Mw = 450000, glass transition temperature is -55 ° C, solid content is 30% by weight, Arkema.

The test methods for the performance parameters involved in the following examples and comparative examples are as follows:

(1) Surface density test of ceramic layer: 10 cm ² × 10 cm ^{2 of} separator paper (ceramic separator before heat-resistant fiber layer was formed) and PE base film, which were weighed by m1 (mg) and m2 (mg), respectively. The film thicknesses were measured as d1 (μm) and d2 (μm, the areal density of the ceramic layer at unit thickness = (m1 - m2) × ρ _Al2O3 / [10 × 10 × (d1 - d2) × 10 ^-4 × ρ Where ρ _Al2O3 is the true density of the aluminum oxide and ρ is the true density of the ceramic particles used;

(2) Ceramic layer gas permeability (Gurley value) test: The ceramic diaphragm was cut into a ceramic diaphragm sample having an area of 6.45 cm ² , and a Gurley value tester GURLEY-4110, pressure (water column height) 12.39 cm was used to measure 100 ml of gas. The time (s/100 ml) required for (air) to pass through the aforementioned ceramic diaphragm sample, the smaller the value, the better the gas permeability.

(3) Test of peeling strength of ceramic layer: A ceramic separator including only a single-sided ceramic layer and not including a heat-resistant fiber layer and a bonding layer was prepared according to the respective processes of the following examples and comparative examples, and 40 mm × 100 mm was cut therefrom. The sample is fixed on both sides of the ceramic diaphragm by a tape on a fixing jig and a movable jig. The 180° C reverse stretching causes the ceramic layer and the base film to be peeled off. The greater the required pulling force, the higher the peeling strength of the ceramic diaphragm. , indicating that the bond strength is higher.

(4) Thermal stability test of ceramic diaphragm: 5cm×5cm ceramic diaphragm samples were cut from the ceramic diaphragm and placed in an oven at 120°C and 160°C for 1 hour, respectively, to compare the area change before and after baking. The ratio of the change in area to the original area (shrinkage) is a measure of the thermal stability of the ceramic diaphragm, not exceeding 5% for A and greater than 5% for B.

(5) Method for measuring the glass transition temperature of the heat-resistant fiber layer material: It was measured by a differential scanning calorimeter manufactured by METTLER.

(6) Method for measuring the liquid absorption rate of the heat-resistant fiber layer material: the material to be tested is dissolved in the corresponding solvent, and cast to form a sample of a specified size (for example, a disk having a diameter of 17 mm), and dried in an argon-filled glove. In the tank (25 ° C), the sample mass m1 is weighed, and then the sample is immersed in an electrolyte (the electrolyte contains a lithium salt LiPF ₆ (lithium hexafluorophosphate) and an organic solvent system, and the content of the lithium salt is 1 mol/L, The organic solvent system contains 32.5% by weight of EC (ethylene carbonate), 32.5% by weight of EMC (ethyl methyl carbonate), and 32.5% by weight of DMC (dimethyl carbonate) based on 100% of the total amount. , 2.5% by weight of VC (vinylene carbonate) in 24h, then take out the sample, use the filter paper to dry the liquid on the surface of the sample (without pressing), and weigh the mass m2 of the sample, then according to the formula Rate = (m2-m1) / m1 × 100%", and the corresponding liquid absorption rate was calculated.

(7) Porous heat-resistant fiber layer porosity test: cut a certain volume of heat-resistant fiber layer sample, weigh, and then immerse the heat-resistant fiber layer sample in n-butanol, and measure the sample weight after adsorption equilibrium.

(8) Bonding layer porosity test: The porous self-crosslinking polymer films Sb1 to Sb14 obtained in Examples 17 to 31 were respectively cut into discs having a diameter of 17 mm, weighed, and then the bonding layer samples were immersed in positive In butanol for 2 h, then take out and blot the liquid on the surface of the membrane with a filter paper and weigh the mass at this time. Calculate the porosity according to the following formula:

P is the porosity, M ₀ is the mass (mg) of the dry film, M is the mass (mg) after soaking for 2 hours in n-butanol, r is the radius (mm) of the film, and d is the thickness (μm) of the film.

(9) Surface density of the bonding layer: a 0.2 m×0.2 m PE base film and a PE base film containing a bonding layer are respectively taken, and the weights thereof are M ₀ (g) and M (g), and the areal density = [(MM ₀ )/0.04] g/m ² .

(10) Adhesive layer liquid absorption rate test: The porous self-crosslinking polymer films Sb1 to Sb14 obtained in Examples 17 to 31 were respectively cut into discs having a diameter of 17 mm, and then referenced to the liquid absorption of the heat-resistant fiber layer material. The rate measurement method is tested.

(11) Test of ionic conductivity of the bonding layer: The porous self-crosslinking polymer films Sb1 to Sb14 obtained in Examples 17 to 31 were respectively cut into discs having a diameter of 17 mm by an alternating current impedance test, and dried, and then placed. Between two stainless steel (SS) electrodes, a sufficient amount of electrolyte is absorbed (the electrolyte contains a lithium salt LiPF ₆ (lithium hexafluorophosphate) and an organic solvent system, and the content of the lithium salt is 1 mol/L, the organic solvent system Based on 100% of the total amount, it contains 32.5% by weight of EC (ethylene carbonate), 32.5% by weight of EMC (ethyl methyl carbonate), 32.5% by weight of DMC (dimethyl carbonate), and 2.5 weight. % VC (vinylene carbonate)), sealed in the 2016 type button battery, and subjected to AC impedance test. The intersection of linear and real axis is the bulk resistance of the electrolyte, and the ionic conductivity of the bonding layer can be obtained. : σ = L / A · R (where L represents the thickness (cm) of the bonding layer, A is the contact area (cm ² ) of the stainless steel plate with the film, and R is the bulk resistance (mS) of the electrolytic solution).

(12) Mechanical strength test: The tensile and puncture properties of the polymer composite membrane prepared in each of the above examples were tested using a universal testing machine of Shenzhen Junrui (all calibrated);

(13) Heat shrinkage test: The polymer composite film prepared in the above example was cut into 6 cm × 6 cm square pieces, placed in an oven, and baked at 120 ° C, 140 ° C, 160 ° C, 180 ° C for 1 h, respectively. Measure the length and width of the square piece. The heat shrinkage rate is calculated as follows: heat shrinkage ratio = (1 - length of sample after heat shrinkage / 6) × 100%.

(14) Ionic conductivity test: The polymer composite film prepared in each of the examples and the comparative examples was cut into a disk having a diameter of 17 mm by an alternating current impedance test, and the test method was as described in the foregoing bonding layer. Conductivity test.

Example 1 (Preparation of PE base film - heat resistant fiber layer two-layer polymer composite film)

This example is intended to illustrate the polymer composite membrane provided by the present disclosure and a method of preparing the same.

(1) Forming a heat resistant fiber layer on the PE base film:

Polyetherimide (commercially available from SABIC Innovative Plastics (Shanghai) Co., Ltd. ultem 1000, melting point of 370-410 ° C, glass transition temperature of 215 ° C, the same below) and polyvinylidene fluoride-hexafluoropropylene (commercially available from Arkema Investment Co., Ltd., the weight average molecular weight is 450,000g/mol, the melting point is 152 ° C, the glass transition temperature is -40 ° C, the liquid absorption rate in the electrolyte at 25 ° C is 45%, the same below ) blended in a ratio of 1:1 by weight, and the blending method uses mechanical agitation to combine the two The mixture was stirred uniformly, the stirring speed was 1200 rpm, and the blend was blended for 2 hours to obtain a blend. The above blend was added to N,N-dimethylpyrrolidone (NMP), and the mixture was fully dissolved by magnetic stirring in a water bath at 70 ° C. A spinning solution having a concentration of 30% by weight was formed.

A 12 μm PE base film (available from SK Corporation of Japan, brand No. BD1201, the same below) was wrapped on the surface of the drum (collection device), and the surface of the PE base film was subjected to a needle electrospinning method. The above spinning solution was subjected to electrospinning. Adjust the electrospinning parameters as follows: receiving distance is 12cm, temperature is 25°C, humidity is 20%, needle inner diameter is 0.46mm, needle moving speed is 6.6mm/sec, voltage is 10kV, flow rate is 0.3mL/h, drum speed It is 2000 rpm.

After the end of the electrospinning, the PE base film was removed, molded under a pressure of 10 MPa for 5 min, and then air-dried at 50 ° C for 24 h to obtain a heat-resistant fiber layer (thickness: 3 μm, porosity: 85%). Polymer composite film F1.

(2) Structure and performance characterization of polymer composite membrane:

As shown in FIG. 1, FIG. 1 is an SEM image of the polymer composite film F1. As shown in FIG. 1, it can be seen that the heat-resistant fiber layer is composed of a plurality of fibers having relatively close thickness, and the heat-resistant fiber layer is formed to contain a large amount of voids. And the voids are evenly distributed, and the ceramic layer under the heat-resistant fiber layer can also be clearly seen. At the same time, it can be seen that a network structure is formed between the fibers.

The diameter of the fiber in the SEM image was measured by TEM Macrography software, and the data was recorded. The final calculated fiber diameter was 176 nm, and the areal density of the heat-resistant fiber layer was 1.22 g/m ² .

The polymer composite film F1 was tested to have a transverse tensile strength and a longitudinal tensile strength of 145 MPa and 148 MPa, a needle punching strength of 0.53 kgf, and an ionic conductivity of 8.0 mS/cm. In addition, the polymer composite film F1 was baked at 120 ° C, 140 ° C, 160 ° C, and 180 ° C for 1 h, respectively, and the transverse heat shrinkage rates were: 1%, 3.5%, 8.2%, 10%, and the longitudinal heat shrinkage rate. They are: 0.8%, 3.3%, 11.5%, and 11.8%.

Example 2 (Preparation of heat-resistant fiber layer - PE base film - heat-resistant fiber layer three-layer structure polymer composite film)

(1) Formation of heat-resistant fiber layer: First, a first heat-resistant fiber layer (thickness: 1.5 μm, porosity: 85%) was formed on one side of the PE base film by the method of Example 1, and then another layer of the PE base film was used. A second heat-resistant fiber layer (having a thickness of 1.5 μm and a porosity of 85%) was formed on one side to obtain a polymer composite film F2.

The polymer composite film F2 was tested to have a transverse tensile strength and a longitudinal tensile strength of 148 MPa and 150 MPa, a needle punching strength of 0.53 kgf, and an ionic conductivity of 8.0 mS/cm. Further, the polymer composite film F2 was baked at 120 ° C, 140 ° C, 160 ° C, and 180 ° C for 1 h, respectively, and the transverse heat shrinkage ratios were 0.9%, 3.2%, 8%, and 9.2%, respectively, and the longitudinal heat shrinkage ratio was They are: 0.75%, 3%, 11%, and 11.5%.

Comparative Example 1 (PE base film)

This comparative example is used to compare the beneficial effects of the polymer composite membrane provided by the present disclosure.

(1) A PE film commercially available from SK Corporation of Japan under the designation BD1201 was used as a comparative sample, and was designated as DF1 (thickness: 12 μm, porosity: 45%).

(2) The transverse tensile strength and the longitudinal tensile strength of the PE film were tested to be 150 MPa and 152 MPa, respectively, the needle punching strength was 0.501 kgf, and the ionic conductivity was 7.9 mS/cm. In addition, the PE film was baked at 120 ° C, 140 ° C, 160 ° C, and 180 ° C for 1 h, and the transverse heat shrinkage rates were 70%, 95%, 95%, and 95%, respectively. The longitudinal heat shrinkage rates were: 75.2%, 96%, 96%, 96%.

Comparative Example 2 (Preparation of PE base film-heat resistant fiber layer two-layer polymer composite film)

(1) Forming a heat resistant fiber layer on a PE base film: Refer to Example 1, except that the spinning solution is magnetically stirred by a water bath at 70 ° C by adding the polyether imide to the NMP solution. The spinning solution having a concentration of 30% by weight was sufficiently dissolved to form a polymer composite film DF2 having a heat-resistant fiber layer formed by electrospinning (the heat-resistant fiber layer had a thickness of 3 μm and a porosity of 82%).

(2) Structure and performance characterization of polymer composite membrane:

The diameter of the fiber in the SEM image was measured by TEM Macrography software, and the data was calculated. The final calculated fiber diameter was 189 nm, and the areal density of the heat-resistant fiber layer was 1.22 g/m ² , which was obtained by the gravimetric method. It is easy to separate or fall off between the filament and the filament, which is difficult to apply. The transverse tensile strength and the longitudinal tensile strength of the polymer composite film DF2 were tested to be 137 MPa and 145 MPa, respectively, the needle punching strength was 0.52 kgf, and the ionic conductivity was 7.9 mS/cm. In addition, the polymer composite film DF2 was baked at 120 ° C, 140 ° C, 160 ° C, and 180 ° C for 1 h, respectively, and the transverse heat shrinkage rates were: 1%, 3.3%, 7.9%, 9.8%, and longitudinal heat shrinkage. The rates were 0.8%, 3.1%, 11.2%, and 11.4%, respectively.

Comparative Example 3 (Preparation of PE base film-heat resistant fiber layer two-layer polymer composite film)

(1) Formation of a heat resistant fiber layer on a PE base film: Refer to Example 1, except that the spinning solution is obtained by adding polyvinylidene fluoride-hexafluoropropylene to an NMP solution under a water bath at 70 ° C. Stirring to dissolve it sufficiently to form a spinning solution having a concentration of 30% by weight, and further obtaining a polymer composite film DF3 having a heat-resistant fiber layer by electrospinning (the heat-resistant fiber layer has a thickness of 3 μm and a porosity of 83.5%). .

(2) Structure and performance characterization of polymer composite membrane:

The diameter of the fiber in the SEM image was measured by TEM Macrography software, and the data was recorded. The final calculated fiber diameter was 129 nm, and the areal density of the heat-resistant fiber layer was calculated by gravimetric method to be 1.07 g/m ² . The transverse tensile strength and the longitudinal tensile strength of the polymer composite film DF3 were tested to be 129 MPa and 142 MPa, respectively, the needling strength was 0.515 kgf, and the ionic conductivity was 8.5 mS/cm. In addition, the polymer composite film DF3 was baked at 120 ° C, 140 ° C, 160 ° C, and 180 ° C for 1 h, respectively, and the transverse heat shrinkage rates were: 10%, 40%, 70%, 91%, and the longitudinal heat shrinkage rate. They are: 10%, 50%, 77%, 95%.

Comparative Example 4 (Preparation of PE base film-heat resistant fiber layer two-layer polymer composite film)

(1) Formation of a heat-resistant fiber layer on a PE base film: Refer to Example 1, except that polyvinylidene fluoride (commercially available from Arkema Co., Ltd., having a weight average molecular weight of 1,000,000 g/mol and a melting point of 172 ° C) was used. The liquid absorption rate in the electrolyte at 25 ° C is 25%) instead of polyvinylidene fluoride-hexafluoropropylene and polyetherimide blending to prepare a spinning solution having a concentration of 30% by weight, and further formed by electrospinning. The polymer composite film DF4 having a heat resistant fiber layer (the heat resistant fiber layer has a thickness of 3 μm and a porosity of 83%).

(2) Structure and performance characterization of polymer composite membrane:

The diameter of the fiber in the SEM image was measured by TEM Macrography software, and the data was recorded. The final calculated fiber diameter was 159 nm, and the areal density of the heat-resistant fiber layer was 1.23 g/m ² , which was obtained by gravimetric method. Compared with fluffy, the fibers are also easier to fall off. The polymer composite film DF4 was tested to have a transverse tensile strength and a longitudinal tensile strength of 143 MPa and 145 MPa, a needle punching strength of 0.53 kgf, and an ionic conductivity of 7.8 mS/cm. In addition, the polymer composite film DF4 was baked at 120 ° C, 140 ° C, 160 ° C, and 180 ° C for 1 h, respectively, and the transverse heat shrinkage rates were: 5%, 7%, 11%, 30%, and the longitudinal heat shrinkage rate. They are: 4.8%, 7.2%, 11.3%, 29.5%.

Example 3 (Preparation of PE base film-ceramic layer-heat resistant fiber layer three-layer structure polymer composite film)

(1) Preparation of ceramic diaphragm:

2 kg of aluminum oxide (average particle diameter of 400 nm), 0.01 kg of sodium polyacrylate (number average molecular weight of 9000, purchased from Guangzhou Yuanchang Trading Co., Ltd.), and 0.024 kg of sodium carboxymethylcellulose (1% by weight aqueous solution) Viscosity is 2500-3000mPaS, purchased from Xinxiang City and Lalida Power Materials Co., Ltd., grade BTT-3000) and mixed with water uniformly, so that the solid content of aluminum oxide is 30% by weight, the mixture is Stir at 6000 rpm for 1.5 hours, then add 0.02 kg of 3-glycidoxypropyltrimethoxysilane and continue to stir for 1.5 hours, then add 0.1 kg of polyacrylate binder (crosslinking monomer is N-hydroxymethyl) Acrylamide and its content was 4% by weight, glass transition temperature was -20 ° C), and stirred at 3000 rpm for 1.5 hours, followed by addition of 0.08 kg of sodium dodecylbenzene sulfonate, followed by 3000 rpm The mixture was stirred for 0.5 hour to obtain a slurry for forming a ceramic layer.

The above ceramic layer slurry was coated on the surface of one side of a 12 μm-thick PE base film (available from SK Corporation of Japan under the designation BD1201, the same below), and dried to obtain a thickness of 2.5 μm on one side surface of the base film. The ceramic layer is obtained to obtain a ceramic separator C1. The ceramic layer of the ceramic separator C1 has an areal density of 2.11 mg/cm ² at a thickness of 1 μm, a gas permeability of 202 s/100 ml, and a peel strength of 5.4 N at 120 ° C. The thermal stability is A, and the thermal stability at 160 ° C is A.

(2) Preparation of heat-resistant fiber layer: Refer to Example 1, except that the ceramic separator C1 prepared as described above was used instead of the porous separator PE, and the method of Example 1 was used to prepare the surface of the ceramic layer of the separator ceramic C1. The heat fiber layer was prepared to form a polymer composite film F3 having a heat resistant fiber layer (thickness: 3 μm, porosity: 79%).

(3) Structure and performance characterization of polymer composite membrane:

The diameter of the fiber in the SEM image was measured by TEM Macrography software, and the data was recorded. The final calculated fiber diameter was 210 nm, and the areal density of the heat-resistant fiber layer was 1.23 g/m ² . The transverse tensile strength and the longitudinal tensile strength of the polymer composite film F3 were tested to be 115 MPa and 120 MPa, respectively, the needle punching strength was 0.544 kgf, and the ionic conductivity was 7.8 mS/cm. In addition, the polymer composite film F3 was baked at 120 ° C, 140 ° C, 160 ° C, and 180 ° C for 1 h, respectively, and the transverse heat shrinkage rates were: 0%, 0%, 1.2%, 3.5%, and the longitudinal heat shrinkage rate. They are: 0%, 0.05%, 2.2%, 5%.

Comparative Example 5 (Preparation of PE base film-ceramic layer two-layer polymer composite film)

(1) Method of preparing ceramic separator: A method of preparing a ceramic separator in the same manner as in (1) of Example 3, the obtained ceramic separator is referred to as DF5 (i.e., the ceramic separator C1 obtained in Example 3).

(2) Structure and performance characterization of polymer composite membrane:

The transverse tensile strength and the longitudinal tensile strength of the polymer composite film DF5 were tested to be 132 MPa and 145 MPa, respectively, the needle punching strength was 0.512 kgf, and the ionic conductivity was 7.8 mS/cm. Further, the polymer composite film DF5 was baked at 120 ° C, 140 ° C, 160 ° C, and 180 ° C for 1 h, respectively, and the transverse heat shrinkage rates were 0.3%, 1%, 6.5%, and 86%, respectively, and the longitudinal heat shrinkage ratio was They are: 0.5%, 1.5%, 5.5%, and 82.2%.

Example 4 (Preparation of PE base film-ceramic layer-heat resistant fiber layer three-layer structure polymer composite film)

This embodiment is for explaining the ceramic separator provided by the present disclosure and a method of producing the same.

(1) a method of preparing a ceramic separator: same as in Example 3, to obtain a ceramic separator C1;

(2) forming a heat-resistant fiber layer: refer to Example 3, except that polyetherimide and polyvinylidene fluoride-hexafluoropropylene are blended in a ratio of 3:1 by weight to prepare a corresponding spinning solution, and A polymer composite film formed with a heat resistant fiber layer (thickness: 3 μm, porosity: 84.2%) was prepared by using the above spinning solution as F4.

(3) Structure and performance characterization of polymer composite membrane:

The diameter of the fiber in the SEM image was measured by TEM Macrography software, and the data was recorded. The final calculated fiber diameter was 186 nm, and the areal density of the heat-resistant fiber layer was 1.22 g/m ² . The transverse tensile strength and the longitudinal tensile strength of the polymer composite film F4 were tested to be 124 MPa and 129 MPa, respectively, the needle punching strength was 0.543 kgf, and the ionic conductivity was 7.5 mS/cm. In addition, the polymer composite film F4 was baked at 120 ° C, 140 ° C, 160 ° C, and 180 ° C for 1 h, respectively, and the transverse heat shrinkage rates were: 0%, 0%, 1.5%, 3.5%, and the longitudinal heat shrinkage rate. They are: 0%, 0%, 2.2%, 4.5%.

Example 5 (Preparation of PE base film-ceramic layer-heat resistant fiber layer three-layer structure polymer composite film)

(1) Preparation of ceramic separator: same as in Example 3, to obtain a ceramic membrane C1;

(2) forming a heat resistant fiber layer: refer to Example 3, except that polyetherimide and polyvinylidene fluoride-hexafluoropropylene are blended at a weight ratio of 5:1 to prepare a corresponding spinning solution, and A polymer composite film formed with a heat resistant fiber layer (thickness: 3 μm, porosity: 83%) was prepared by using the above spinning solution as F5.

(3) Structure and performance characterization of polymer composite membrane:

The diameter of the fiber in the SEM image was measured by TEM Macrography software, and the data was recorded. The final calculated fiber diameter was 186 nm, and the areal density of the heat-resistant fiber layer was 1.22 g/m ² .

The polymer composite film F5 was tested to have a transverse tensile strength and a longitudinal tensile strength of 125 MPa and 129 MPa, a needle punching strength of 0.543 kgf, and an ionic conductivity of 6.9 mS/cm. In addition, the polymer composite film F5 was baked at 120 ° C, 140 ° C, 160 ° C, and 180 ° C for 1 h, respectively, and the transverse heat shrinkage rates were: 0%, 0.5%, 2.5%, 3.6%, and the longitudinal heat shrinkage rate. They are: 0%, 1.3%, 3%, 4.6%.

Example 6 (Preparation of PE base film-ceramic layer-heat resistant fiber layer three-layer structure polymer composite film)

(2) forming a heat-resistant fiber layer: refer to Example 3, except that polyetherimide and polyvinylidene fluoride-hexafluoropropylene are blended at a weight ratio of 10:1 to prepare a corresponding spinning solution, and A polymer composite film which was formed into the heat-resistant fiber layer (thickness: 3 μm, porosity: 86.4%) was prepared by the above-mentioned spinning solution, and was designated as F6.

(3) Structure and performance characterization of polymer composite membrane:

The diameter of the fiber in the SEM image was measured by TEM Macrography software, and the data was recorded. The final calculated fiber diameter was 222 nm, and the areal density of the heat-resistant fiber layer was 1.19 g/m ² .

The polymer composite film F6 was tested to have a transverse tensile strength and a longitudinal tensile strength of 121 MPa and 125 MPa, a needle punching strength of 0.564 kgf, and an ionic conductivity of 7.3 mS/cm. In addition, the polymer composite film F6 was baked at 120 ° C, 140 ° C, 160 ° C, and 180 ° C for 1 h, respectively, and the transverse heat shrinkage rates were: 0%, 0.5%, 3.5%, 5.5%, and the longitudinal heat shrinkage rate. They are: 0%, 1.3%, 3%, 7.5%. In the polymer composite film F6, the ionic conductivity is improved due to an increase in porosity, whereas the viscosity of the formed heat-resistant fiber layer is deteriorated due to a low content of polyvinylidene fluoride-hexafluoropropylene. Thus, the tensile properties of the polymer composite film F6 are weakened, and the heat shrinkage property is also lowered.

Example 7 (Preparation of PE base film-ceramic layer-heat resistant fiber layer three-layer structure polymer composite film)

(2) Formation of heat-resistant fiber layer: Refer to Example 3, except that polyethylene oxide (commercially available from Aladdin, having a weight average molecular weight of 600,000 g/mol, a melting point of 130 ° C, and a glass transition temperature of -62 ° C) was used. , the liquid absorption rate in the electrolyte at 25 ° C is 1000%) in place of the above polyvinylidene fluoride-hexafluoropropylene to prepare a spinning solution, and the above-mentioned spinning solution is used to prepare a heat-resistant fiber layer (thickness of 3 μm, pores) A polymer composite film F7 having a rate of 85%).

(3) Structure and performance characterization of polymer composite membrane:

The diameter of the fiber in the SEM image was measured by TEM Macrography software, and the data was recorded. The final calculated fiber diameter was 230 nm, and the areal density of the heat-resistant fiber layer was 1.30 g/m ² .

The polymer composite film F7 was tested to have a transverse tensile strength and a longitudinal tensile strength of 123 MPa and 137 MPa, a needle punching strength of 0.529 kgf, and an ionic conductivity of 7.9 mS/cm. In addition, the polymer composite film F7 was baked at 120 ° C, 140 ° C, 160 ° C, and 180 ° C for 1 h, respectively, and the transverse heat shrinkage rates were: 0%, 1.5%, 3%, 8.6%, and the longitudinal heat shrinkage rate. They are: 0%, 1.15%, 2.5%, 8.3%.

Example 8 (Preparation of PE base film-ceramic layer-heat resistant fiber layer three-layer structure polymer composite film)

(2) Forming a heat resistant fiber layer:

Adding polyetherimide to the NMP solution, magnetically stirring in a water bath at 70 ° C to dissolve it sufficiently to form a spinning solution A having a concentration of 30 wt%; adding polyvinylidene fluoride-hexafluoropropylene to the NMP solution, The magnetic solution was fully stirred in a water bath at 70 ° C to form a spinning solution B having a concentration of 30 wt%.

The ceramic separator C1 prepared as described above is wrapped on a drum (collection device), and the spinning solution A and the spinning solution B are electrospun on the surface of the ceramic separator C1 on which the ceramic layer is formed by a needle electrospinning method. Wherein the weight ratio of the polyetherimide in the spinning solution A to the polyvinylidene fluoride-hexafluoropropylene in the spinning solution B was 1:1. Adjust the electrospinning parameters as follows: receiving distance is 12cm, temperature is 25°C, humidity is 50%, needle inner diameter is 0.46mm, needle moving speed is 6.6mm/sec, voltage is 10kV, flow rate is 0.3mL/h, drum speed It is 2000 rpm.

After the end of the electrospinning, the ceramic separator was removed, molded at a pressure of 15 MPa for 1 min, and then air-dried at 50 ° C for 24 h to obtain a polymer having a heat-resistant fiber layer (thickness: 3 μm, porosity: 81.3%). Composite film F8.

(3) Structure and performance characterization of polymer composite membrane:

The diameter of the fiber in the SEM image was measured by TEM Macrography software, and the data was recorded. The final calculated fiber diameter was 246 nm, and the areal density of the heat-resistant fiber layer was calculated by gravimetric method to be 1.31 g/m ² .

The transverse tensile strength and the longitudinal tensile strength of the polymer composite film F8 were tested to be 118 MPa and 122 MPa, respectively, the needle punching strength was 0.544 kgf, and the ionic conductivity was 7.6 mS/cm. In addition, the polymer composite film F8 was baked at 120 ° C, 140 ° C, 160 ° C, and 180 ° C for 1 h, respectively, and the transverse heat shrinkage rates were: 0%, 0%, 1.3%, 3.8%, and the longitudinal heat shrinkage rate. They are: 0%, 0.05%, 2.3%, 5.5%.

Example 9 (Preparation of PE base film-ceramic layer-heat resistant fiber layer three-layer structure polymer composite film)

(1) Preparation of ceramic diaphragm:

2kg boehmite (average particle size 300nm), 0.016kg sodium polyacrylate (number average molecular weight 9000, purchased from Guangzhou Yuanchang Trading Co., Ltd.), 0.014kg carboxymethyl nanocellulose sodium (1% by weight aqueous solution) Viscosity is 2500-3000mPaS, purchased from Xinxiang City and Lalida Power Materials Co., Ltd., grade BTT-3000) and water is evenly mixed, so that the mixture of boehmite solid content is 50% by weight, the mixture is at 8000rpm Stir for 1.5 hours, then add 0.01 kg of 3-glycidoxypropyltrimethoxysilane and continue to stir for 1.5 hours, then add 0.12 kg of polyacrylate binder (crosslinking monomer is N-methylol propylene) The amide was contained in an amount of 3% by weight, the glass transition temperature was -40 ° C), and stirred at 3000 rpm for 1.5 hours, followed by the addition of 0.08 kg of sodium dodecylbenzenesulfonate and stirring at 3000 rpm for 1.5 hours to form Ceramic layer slurry.

The above ceramic layer slurry was coated on one side surface of a 12 μm thick PE base film, and dried to obtain a ceramic layer having a thickness of 2 μm on one side surface of the base film to obtain a product ceramic separator C2, which was tested. The ceramic layer of the ceramic separator C2 has an areal density of 2.02 mg/cm ² at a thickness of 1 μm, a gas permeability of 198 s/100 ml, a peel strength of 5.6 N, a thermal stability at 120 ° C of A, and a thermal stability at 160 ° C. Is A.

(2) Formation of heat-resistant fiber layer: Refer to Example 3, except that the ceramic separator C2 prepared as described above was used instead. In the ceramic separator C1, a polymer composite film having a heat-resistant fiber layer (thickness: 3 μm, porosity: 79%) was obtained as F9.

(3) Characterization of polymer composite membrane:

The polymer composite film F9 was tested to have a transverse tensile strength and a longitudinal tensile strength of 120 MPa and 125 MPa, a needle punching strength of 0.544 kgf, and an ionic conductivity of 7.8 mS/cm. In addition, the polymer composite film F9 was baked at 120 ° C, 140 ° C, 160 ° C, and 180 ° C for 1 h, respectively, and the transverse heat shrinkage rates were: 0%, 0%, 1.3%, 3.8%, and the longitudinal heat shrinkage rate. They are: 0%, 0.05%, 2.3%, 5.35%.

Example 10 (Preparation of PE base film-ceramic layer-heat resistant fiber layer three-layer structure polymer composite film)

(1) Preparation of ceramic diaphragm:

2 kg of titanium dioxide (average particle size of 500 nm), 0.008 kg of sodium polyacrylate (number average molecular weight of 9000, purchased from Guangzhou Yuanchang Trading Co., Ltd.), 0.03 kg of sodium carboxymethyl nanocellulose (1% by weight aqueous solution viscosity is 2500-3000mPaS, purchased from Xinxiang City and Lalida Power Materials Co., Ltd., brand BTT-3000) and water mixed evenly, so that the solid content of titanium dioxide is 25% by weight mixture, the mixture is stirred at 4000rpm for 1.5 hours Then, 0.024 kg of 3-glycidoxypropyltrimethoxysilane was added and stirring was continued for 1.5 hours, and then 0.08 kg of a polyacrylate binder (crosslinking monomer hydroxymethyl acrylate and its content was 5% by weight) was added. The glass transition temperature was 0 ° C), and stirred at 3000 rpm for 1.5 hours, followed by the addition of 0.08 kg of sodium dodecylbenzenesulfonate and stirring at 3000 rpm for 1.5 hours to obtain a slurry for forming a ceramic layer.

The above ceramic layer slurry was coated on one side surface of a 12 μm thick PE base film, and dried to obtain a ceramic layer having a thickness of 3.5 μm on one side surface of the base film to obtain a product ceramic separator C3. The ceramic layer of the ceramic separator C3 has an areal density of 2.05 mg/cm ² at a thickness of 1 μm, a gas permeability of ^{200 s} /100 ml, a peel strength of 5.7 N, a thermal stability at 120 ° C of A, and thermal stability at 160 ° C. Sex is A.

(2) Formation of heat-resistant fiber layer: Refer to Example 3, except that the ceramic separator C3 prepared as described above was used instead of the ceramic separator C1, and a polymer having a heat-resistant fiber layer (thickness: 3 μm, porosity: 81.5%) was obtained. The composite membrane was designated as F10.

(3) Characterization of polymer composite membrane:

The transverse tensile strength and the longitudinal tensile strength of the polymer composite film F10 were tested to be 113 MPa and 118 MPa, respectively, the needle punching strength was 0.544 kgf, and the ionic conductivity was 7.7 mS/cm. Further, the polymer composite film F10 was baked at 120 ° C, 140 ° C, 160 ° C, and 180 ° C for 1 h, respectively, and the transverse heat shrinkage ratios were: 0%, 0%, 1.3%, 3.6%, and the longitudinal heat shrinkage ratio. They are: 0%, 0.06%, 2.3%, 5.3%.

Example 11 (Preparation of PE base film-ceramic layer-heat resistant fiber layer three-layer structure polymer composite film)

(1) Preparation of ceramic separator: Refer to Example 3, except that the amount of the polyacrylate binder in the preparation of the ceramic layer slurry was 0.06 kg, and the content of the crosslinking monomer in the polyacrylate binder was 7% by weight. A ceramic separator C4 was obtained, and the ceramic layer of the ceramic separator C4 was tested to have an areal density of 1.95 mg/cm ² , a gas permeability of 208 s/100 ml, a peel strength of 4.3 N, and a thermal stability at 120 ° C of A. The thermal stability at 160 ° C is A.

(2) Formation of heat-resistant fiber layer: Refer to Example 1, except that the ceramic separator C1 prepared as described above was used instead of the ceramic separator C1 to obtain a polymer composite film F11 having a heat-resistant fiber layer formed thereon.

(3) Characterization of polymer composite membrane:

The transverse tensile strength and the longitudinal tensile strength of the polymer composite film F11 were tested to be 115 MPa and 121 MPa, respectively, the needle punching strength was 0.544 kgf, and the ionic conductivity was 7.6 mS/cm. Further, the polymer composite film F11 was baked at 120 ° C, 140 ° C, 160 ° C, and 180 ° C for 1 h, respectively, and the transverse heat shrinkage ratios were: 0%, 0%, 1.7%, 4.0%, and the longitudinal heat shrinkage ratio. They are: 0%, 0.08%, 2.5%, 5.5%.

Example 12 (Preparation of PE base film-ceramic layer-heat resistant fiber layer three-layer structure polymer composite film)

(1) Preparation of ceramic separator: Refer to Example 3, except that the amount of the polyacrylate binder used in preparing the ceramic layer slurry was 0.12 kg, and the content of the crosslinking monomer in the polyacrylate binder was 5% by weight. And without adding 3-glycidoxypropyltrimethoxysilane, the ceramic separator C5 was obtained, and the ceramic layer of the ceramic separator C5 was tested to have an areal density of 1.91 mg/cm ² and a gas permeability of 212 s/100 ml. The strength is 4.5 N, the thermal stability at 120 ° C is A, and the thermal stability at 160 ° C is A.

(2) Formation of heat-resistant fiber layer: Refer to Example 1, except that the above-prepared amount of the ceramic separator C5 was used instead of the porous separator PE to obtain a polymer composite film F12 having a heat-resistant fiber layer formed thereon.

(3) Characterization of polymer composite membrane:

The polymer composite film F12 was tested to have a transverse tensile strength and a longitudinal tensile strength of 116 MPa and 120 MPa, a needle punching strength of 0.544 kgf, and an ionic conductivity of 7.5 mS/cm. In addition, the polymer composite film F12 was baked at 120 ° C, 140 ° C, 160 ° C, and 180 ° C for 1 h, respectively, and the transverse heat shrinkage rates were: 0%, 0.08%, 2.3%, 4.2%, and the longitudinal heat shrinkage rate. They are: 0%, 0.1%, 2.6%, 5.8%.

Example 13 (Preparation of PE base film-ceramic layer-heat resistant fiber layer three-layer structure polymer composite film)

(1) Preparation of ceramic separator: Refer to Example 3, except that the amount of the polyacrylate binder in the preparation of the ceramic layer slurry was 0.08 kg, and the content of the crosslinking monomer in the polyacrylate binder was 2% by weight. A ceramic separator C6 was obtained. The ceramic layer of the ceramic separator C6 was tested to have an areal density of 2 mg/cm ² , a gas permeability of 207 s/100 ml, a peel strength of 4.6 N, and a thermal stability at 120 ° C of A, 160. The thermal stability at °C is A.

(2) Formation of heat-resistant fiber layer: Refer to Example 3 except that the ceramic separator C6 prepared as described above was used instead of the ceramic separator C1 to obtain a polymer composite film F13 having a heat-resistant fiber layer formed thereon.

(3) Characterization of polymer composite membrane:

The transverse tensile strength and the longitudinal tensile strength of the polymer composite film F13 were tested to be 115 MPa and 122 MPa, respectively, the needle punching strength was 0.544 kgf, and the ionic conductivity was 7.4 mS/cm. In addition, the polymer composite film F13 was baked at 120 ° C, 140 ° C, 160 ° C, and 180 ° C for 1 h, respectively, and the transverse heat shrinkage rates were: 0%, 0%, 1.9%, 4.5%, and the longitudinal heat shrinkage rate. They are: 0%, 0.05%, 2.2%, 5.5%.

Example 14 (Preparation of PE base film-ceramic layer-heat resistant fiber layer three-layer structure polymer composite film)

(1) Preparation of ceramic separator: Refer to Example 3 except that the average particle diameter of the aluminum oxide was 700 nm, and the ceramic separator C7 was obtained. The surface density of the ceramic layer of the ceramic separator C7 was 2.11 mg/cm ^{2 .} The gas permeability is 205 s/100 ml, the peel strength is 4.7 N, the thermal stability at 120 ° C is A, and the thermal stability at 160 ° C is A.

(2) Formation of heat-resistant fiber layer: Refer to Example 3 except that the ceramic separator C7 prepared as described above was used instead of the ceramic separator C1 to obtain a polymer composite film F14 having a heat-resistant fiber layer formed thereon.

(3) Characterization of polymer composite membrane:

The polymer composite film F14 was tested to have a transverse tensile strength and a longitudinal tensile strength of 116 MPa and 120 MPa, a needle punching strength of 0.544 kgf, and an ionic conductivity of 7.2 mS/cm. In addition, the polymer composite film F14 was baked at 120 ° C, 140 ° C, 160 ° C, and 180 ° C for 1 h, respectively, and the transverse heat shrinkage rates were: 0%, 0%, 1.2%, 3.5%, and the longitudinal heat shrinkage rate. They are: 0%, 0.05%, 2.2%, 5%.

Example 15 (Preparation of PE base film-ceramic layer-heat resistant fiber layer three-layer structure polymer composite film)

(1) Preparation of ceramic separator: Refer to Example 3 except that the average particle diameter of the aluminum oxide was 250 nm, and the ceramic separator C8 was obtained. The surface density of the ceramic layer of the ceramic separator C8 was 1.91 mg/cm ^{2 .} The gas permeability is 208 s/100 ml, the peel strength is 4.8 N, the thermal stability at 120 ° C is A, and the thermal stability at 160 ° C is A.

(2) Formation of heat-resistant fiber layer: Refer to Example 3, except that the ceramic separator C8 prepared as described above is used instead of ceramic The porcelain separator C1 is obtained as a polymer composite film F15 in which a heat resistant fiber layer is formed.

(3) Characterization of polymer composite membrane:

The transverse tensile strength and the longitudinal tensile strength of the polymer composite film F15 were tested to be 115 MPa and 124 MPa, respectively, the needle punching strength was 0.544 kgf, and the ionic conductivity was 7.0 mS/cm. In addition, the polymer composite film F15 was baked at 120 ° C, 140 ° C, 160 ° C, and 180 ° C for 1 h, respectively, and the transverse heat shrinkage rates were: 0%, 0%, 1.5%, 3.8%, and the longitudinal heat shrinkage rate. They are: 0%, 0.08%, 2.4%, 5.2%.

Example 16 (Preparation of ceramic layer-PE base film-ceramic layer-heat resistant fiber layer four-layer polymer composite film)

(1) Preparation of a ceramic layer: First, a first ceramic layer (thickness: 1.25 μm) was formed on one side of the PE base film by the method of Example 3, and then a second ceramic layer was formed on the other side of the PE base film ( a thickness of 1.25 μm), forming a ceramic diaphragm C9;

(2) Formation of heat-resistant fiber layer: A heat-resistant fiber layer (thickness: 3 μm, porosity: 85%) was formed on the surface of the first ceramic layer in the ceramic separator C9 by the method of Example 3 to obtain a polymer composite film. F16.

The polymer composite film F16 was tested to have a transverse tensile strength and a longitudinal tensile strength of 117 MPa and 122 MPa, a needle punching strength of 0.53 kgf, and an ionic conductivity of 7.8 mS/cm. In addition, the polymer composite film F16 was baked at 120 ° C, 140 ° C, 160 ° C, and 180 ° C for 1 h, respectively, and the transverse heat shrinkage rates were: 0%, 0%, 1.2%, 3.5%, and the longitudinal heat shrinkage rate. They are: 0%, 0.05%, 2.2%, 5%.

Example 17 (Preparation of heat-resistant fiber layer-ceramic layer-PE base film-ceramic layer-heat-resistant fiber layer five-layer structure polymer composite film)

(1) Preparation of ceramic layer: In the same manner as in Example 16, a ceramic separator C9 was obtained.

(2) Formation of heat-resistant fiber layer: First, a first heat-resistant fiber layer (thickness: 3 μm, porosity: 85%) was formed on the surface of the first ceramic layer in the ceramic separator C9 by the method of Example 3, and then A second heat-resistant fiber layer (thickness: 3 μm, porosity: 85%) was formed on the surface of the second ceramic layer in the ceramic separator C9 to obtain a polymer composite film F17.

The transverse tensile strength and the longitudinal tensile strength of the polymer composite film F17 were tested to be 115 MPa and 121 MPa, respectively, and the needle punching strength was 0.53 kgf, and the ionic conductivity was 7.8 mS/cm. Further, the polymer composite film F17 was baked at 120 ° C, 140 ° C, 160 ° C, and 180 ° C for 1 h, respectively, and the transverse heat shrinkage rates were: 0%, 0%, 1%, 3.2%, and the longitudinal heat shrinkage ratio. They are: 0%, 0.04%, 2%, 4.5%.

Example 18 (Preparation of PE base film-ceramic layer-heat resistant fiber layer-bonding layer four-layer structure polymer composite film)

(1) Preparation of Ceramic Separator: In the same manner as in Example 3, a ceramic separator C1 was obtained.

(2) Formation of heat-resistant fiber layer: In the same manner as in Example 3, a polymer composite film F3 was obtained.

(3) Forming a bonding layer:

Self-crosslinking type pure acrylic emulsion (Shanghai Aiyi Chemical Co., Ltd., grade 1040), self-crosslinking type pure acrylic emulsion (Shanghai Aiyi Chemical Co., Ltd., grade 1005) and self-crosslinking type styrene-acrylic emulsion (Shanghai Aihao Chemical Co., Ltd., grade S601) is mixed at a mass ratio of 9:1:10, and added with an appropriate amount of water, and uniformly stirred to form a slurry having a total solid content of 1% by weight;

The above slurry was sprayed onto the surface of the heat-resistant fiber layer in the polymer composite film F3 and on one side surface of the PTFE plate by a spraying method (spraying temperature: 40 ° C), and then dried at 50 ° C to obtain a paste including a polymer composite film Sa1 having a layer (porous self-crosslinking polymer film, the same below) and a porous self-crosslinking polymer film Sb1 on a PTFE plate, wherein the bonding layer has a single face density of 0.1 g/m ² , the thickness of one side is 0.2 μm; and the porous self-crosslinking polymer film Sb1 prepared as described above has a porosity of 62%, a liquid absorption rate of 263%, and a conductivity of 8.33 mS/cm. And the ionic conductivity of the polymer composite film Sa1 was 8.3 mS/cm.

The bonding layer was subjected to a comparative example (preparation of a PE-based film-ceramic layer-heat-resistant fiber layer-bonding layer four-layer polymer composite film)

This comparative example is used to compare and explain the polymer composite membrane provided by the present disclosure and a preparation method thereof.

(3) Formation of a bonding layer: a slurry and a bonding layer were prepared in accordance with the method of Example 18, except that the bonding layer was formed by a doctor blade method to obtain a polymer composite film Da1 including a bonding layer, respectively. The dense self-crosslinking polymer film Db1 on the PTFE sheet, wherein the dense self-crosslinking polymer film had a single-face density of 1.5 g/m ² and a single-sided thickness of 3 μm. Further, the porous self-crosslinking polymer film Db1 prepared as described above was found to have a porosity of 0%, a liquid absorption rate of 130%, and a conductivity of 5.11 mS/cm. And the polymer composite membrane Da1 was tested to have an ionic conductivity of 5.05 mS/cm.

Example 19 (Preparation of PE base film-ceramic layer-heat resistant fiber layer-bonding layer four-layer structure polymer composite film)

(3) Forming a bonding layer:

Copolymerization emulsion of vinylidene fluoride and hexafluoropropylene (Arkema, grade 10278), self-crosslinking pure acrylic emulsion (Shanghai Ai Gao Chemical Co., Ltd., grade 1005) and self-crosslinking styrene-acrylic emulsion (Shanghai Ai Gao Chemical Co., Ltd., grade S601) is mixed at a mass ratio of 12:4:4, and added with an appropriate amount of water, and uniformly mixed to form a tie layer slurry having a total solid content of 5% by weight.

The above-mentioned adhesive layer paste was printed on the surface of the heat-resistant fiber layer in the polymer composite film F3 by a screen printing method (temperature: 75 ° C) and on one side surface of the PTFE plate, and then Drying at 50 ° C, respectively, obtained a polymer composite film Sa2 comprising a bonding layer and a porous self-crosslinking polymer film Sb2 on a PTFE plate, wherein the single layer density of the bonding layer was 0.2 g/m ² , The surface thickness was 0.4 μm; and the porous self-crosslinking polymer film Sb2 prepared as described above was found to have a porosity of 48%, a liquid absorption rate of 192%, and a conductivity of 7.52 mS/cm. And the ionic conductivity of the polymer composite film Sa2 was tested to be 7.45 mS/cm.

Example 20 (Preparation of PE base film-ceramic layer-heat resistant fiber layer-bonded layer four-layer polymer composite film)

(3) Forming a bonding layer:

Self-crosslinking type pure acrylic emulsion (Shanghai Ai Gao Chemical Co., Ltd., grade 1040), copolymerized emulsion of vinylidene fluoride and hexafluoropropylene (Arkema, grade 10278), self-crosslinking type pure acrylic emulsion (Shanghai Ai Gao Chemical Co., Ltd., grade 1005) and self-crosslinking styrene-acrylic emulsion (Shanghai Ai Gao Chemical Co., Ltd., grade S601) are mixed at a solid content of 12:6:1:1, and added with appropriate amount of water. The mixture was uniformly mixed to form a tie layer slurry having a total solid content of 10% by weight.

The above-mentioned adhesive layer slurry was sprayed onto the surface of the heat-resistant fiber layer in the polymer composite film F3 and on one side surface of the PTFE plate by spraying (temperature: 58 ° C), and then dried at 50 ° C to obtain The polymer composite film Sa3 including the adhesive layer and the porous self-crosslinking polymer film Sb3 on the PTFE plate, wherein the adhesive layer had a single face density of 0.3 g/m ² and a single face thickness of 0.3 μm. The porous self-crosslinking polymer film Sb3 prepared as described above was found to have a porosity of 51%, a liquid absorption rate of 300%, and a conductivity of 7.14 mS/cm. And the ionic conductivity of the polymer composite film Sa3 was 7.04 mS/cm.

Example 21 (Preparation of PE base film-ceramic layer-heat resistant fiber layer-bonding layer four-layer structure polymer composite film)

(3) Forming a bonding layer:

Self-crosslinking pure acrylic emulsion (Shanghai Ai Gao Chemical Co., Ltd., grade 1040), copolymerized emulsion of vinylidene fluoride and hexafluoropropylene (Arkema, grade 10278) and self-crosslinking pure acrylic emulsion (Shanghai Ai Gao Chemical Co., Ltd., grade 1005) is mixed at a mass ratio of solid content of 12.7:6.3:1, and an appropriate amount of water is added, and uniformly stirred to form a tie layer slurry having a total solid content of 1% by weight.

The above-mentioned adhesive layer paste was printed by screen printing (temperature: 40 ° C) onto the surface of the heat-resistant fiber layer in the polymer composite film F3 and on one side surface of the PTFE plate, and then dried at 50 ° C. The polymer composite film Sa4 including the adhesive layer and the porous self-crosslinking polymer film Sb4 on the PTFE plate were respectively obtained, wherein the adhesive layer had a single-face density of 0.1 g/m ² and a single-sided thickness of 0.2 μm. The porous self-crosslinking polymer film Sb4 prepared as described above was found to have a porosity of 53%, a liquid absorption rate of 317%, and a conductivity of 7.52 mS/cm. And the ionic conductivity of the polymer composite film Sa4 was 7.5 mS/cm.

Example 22 (Preparation of bonding layer-PE base film-ceramic layer-heat-resistant fiber layer-bonding layer five-layer structure polymer composite film)

(3) Forming a bonding layer:

Self-crosslinking type pure acrylic emulsion (Shanghai Ai Gao Chemical Co., Ltd., grade 1040), self-crosslinking type pure acrylic emulsion (Shanghai Ai Gao Chemical Co., Ltd., grade 1005) and self-crosslinking type styrene-acrylic emulsion (Shanghai Ai Gao Chemical Co., Ltd., grade S601) was mixed at a mass ratio of 6:1:13, and an appropriate amount of water was added thereto, and uniformly stirred to form a binder layer slurry having a total solid content of 5% by weight.

The slurry was sprayed onto the surface of the heat-resistant fiber layer in the polymer composite film F3 and on one side surface of the PTFE plate by a spraying method (temperature: 75 ° C), and then dried at 50 ° C to obtain a paste including The layered polymer composite film Sa5 and the porous self-crosslinking polymer film b5 on the PTFE plate, wherein the bonding layer had a single face density of 0.2 g/m ² and a single face thickness of 0.3 μm. The porous self-crosslinking polymer film Sb5 prepared as described above was found to have a porosity of 46%, a liquid absorption rate of 220%, and a conductivity of 7.39 mS/cm. And the ionic conductivity of the polymer composite film Sa5 was tested to be 7.19 mS/cm.

Example 23 (Preparation of PE base film-ceramic layer-heat resistant fiber layer-bonding layer four-layer structure polymer composite film)

(3) Forming a bonding layer:

Self-crosslinking pure acrylic emulsion (Shanghai Ai Gao Chemical Co., Ltd., grade 1040), copolymerized emulsion of vinylidene fluoride and hexafluoropropylene (Arkema, grade 10278) and self-crosslinking pure acrylic emulsion (Shanghai Ai Gao Chemical Co., Ltd., grade 1005) was mixed at a mass ratio of 11.4:7.6:1, and added with an appropriate amount of water, and uniformly mixed to form a tie layer slurry having a total solid content of 10% by weight.

The above slurry was printed by screen printing (temperature: 75 ° C) onto the surface of the heat-resistant fiber layer in the polymer composite film F3 and on one side surface of the PTFE plate, and then dried at 50 ° C to obtain The polymer composite film Sa6 including the adhesive layer and the adhesive layer Sb6 on the PTFE plate, wherein the adhesive layer had a single face density of 0.3 g/m ² and a single face thickness of 0.6 μm. The porous self-crosslinking polymer film Sb6 prepared as described above was found to have a porosity of 55%, a liquid absorption rate of 287%, and a conductivity of 7.91 mS/cm. And the ionic conductivity of the polymer composite film Sa6 was 7.81 mS/cm.

Example 24 (Preparation of PE base film-ceramic layer-heat resistant fiber layer-bonding layer four-layer structure polymer composite film)

(3) Forming a bonding layer:

Self-crosslinking pure acrylic emulsion (Shanghai Ai Gao Chemical Co., Ltd., grade 1040), copolymerized emulsion of vinylidene fluoride and hexafluoropropylene (Arkema, grade 10278) and self-crosslinking pure acrylic emulsion (Shanghai Ai Gao Chemical Co., Ltd., grade 1005) is mixed at a mass ratio of 9.5:9.5:1, and an appropriate amount of water is added, and uniformly stirred to form a tie layer slurry having a total solid content of 1% by weight.

(2) spraying the above slurry onto the surface of the heat-resistant fiber layer in the polymer composite film F3 and on one side surface of the PTFE plate by spraying (temperature: 40 ° C), and then drying at 50 ° C, respectively A polymer composite film Sa7 comprising a bonding layer and a porous self-crosslinking polymer film Sb7 on a PTFE plate were obtained, wherein the bonding layer had a single-face density of 0.1 g/m ² and a single-sided thickness of 0.2 μm. The porous self-crosslinking polymer film Sb7 prepared as described above was found to have a porosity of 59%, a liquid absorption rate of 252%, and a conductivity of 8.12 mS/cm. And the polymer composite film Sa7 was tested to have an ionic conductivity of 8 mS/cm.

Example 25 (Preparation of PE base film-ceramic layer-heat resistant fiber layer-bonding layer four-layer polymer composite film)

(3) Forming a bonding layer:

Copolymerization emulsion of vinylidene fluoride and hexafluoropropylene (Arkema, grade 10278) and self-crosslinking pure acrylic emulsion (on Hai Aigao Chemical Co., Ltd., grade 1005) is mixed at a mass ratio of solid content of 19:1, and an appropriate amount of water is added, and uniformly stirred to form a binder layer slurry having a total solid content of 5% by weight.

(2) The above slurry was printed by screen printing (temperature: 75 ° C) onto the surface of the heat-resistant fiber layer in the polymer composite film F3 and on one side surface of the PTFE plate, and then dried at 50 ° C. The polymer composite film Sa8 including the adhesive layer and the porous self-crosslinking polymer film Sb8 on the PTFE plate were respectively obtained, wherein the adhesive layer had a single-face density of 0.2 g/m ² and a thickness of 0.4 μm. The porous self-crosslinking polymer film Sb8 prepared as described above was found to have a porosity of 54%, a liquid absorption rate of 76%, and a conductivity of 7.86 mS/cm. And the polymer composite film Sa8 was tested to have an ionic conductivity of 7.6 mS/cm.

Example 26 (Preparation of PE base film-ceramic layer-heat resistant fiber layer-bonding layer four-layer structure polymer composite film)

(3) Forming a bonding layer:

Copolymerization emulsion of vinylidene fluoride and hexafluoropropylene (Arkema, grade 10278) and self-crosslinking pure acrylic emulsion (Shanghai Ai Gao Chemical Co., Ltd., grade 1005) were mixed at a mass ratio of 18:2. And adding an appropriate amount of water, and uniformly mixing to form a bonding layer slurry having a total solid content of 10% by weight.

The slurry was sprayed onto the surface of the heat-resistant fiber layer in the polymer composite film F3 and on one side surface of the PTFE plate by a spraying method (temperature: 58 ° C), and then dried at 50 ° C to obtain a paste including The layered polymer composite film Sa9 and the porous self-crosslinking polymer film Sb9 on the PTFE plate, wherein the bonding layer had a single-face density of 0.3 g/m ² and a single-sided thickness of 0.6 μm. The porous self-crosslinking polymer film Sb9 prepared as described above was found to have a porosity of 47%, a liquid absorption rate of 112%, and a conductivity of 7.4 mS/cm. And the polymer composite film Sa9 was tested to have an ionic conductivity of 7.3 mS/cm.

Example 27 (Preparation of PE base film-ceramic layer-heat resistant fiber layer-bonded layer four-layer polymer composite film)

(2) Formation of heat-resistant fiber layer: In the same manner as in Example 3, a polymer composite film F2 was obtained.

(3) Forming a bonding layer: Refer to Example 17, except that the bonding layer slurry further contains a copolymer emulsion of acrylonitrile and acrylate (Shanghai Ai Gao Chemical Co., Ltd., grade A1030, polyacrylonitrile segment) 15% by weight, polybutyl acrylate segment accounted for 30% by weight, polymethyl methacrylate segment accounted for 45% by weight, polyethyl acrylate segment accounted for 5% by weight, polyacrylic acid segment accounted for 5% by weight, glass The transformation temperature was Tg = 28 ° C, the solid content was 50% by weight, and the weight ratio of the solid content of A1030 to the total solid content of 1040 and 1005 was 1:1.

The adhesive layer slurry was sprayed onto the surface of the heat resistant fiber layer in the polymer composite film F and on one side surface of the PTFE plate by spraying (temperature: 40 ° C), and then dried at 50 ° C to obtain The polymer composite film Sa10 including the adhesive layer and the porous self-crosslinking polymer film Sb10 on the PTFE plate, wherein the adhesive layer had a single face density of 0.1 g/m ² and a single face thickness of 0.2 μm. The porous self-crosslinking polymer film Sb10 prepared as described above was found to have a porosity of 48%, a liquid absorption rate of 293%, and a conductivity of 7.88 mS/cm. And the polymer composite film Sa10 was tested to have an ionic conductivity of 7.7 mS/cm.

Example 28 (Preparation of PE base film-ceramic layer-heat resistant fiber layer-bonding layer four-layer structure polymer composite film)

(3) Forming a bonding layer: refer to Example 17, except that the bonding layer slurry further contains a chloropropene emulsion (Shanghai Ai Gao Chemical Co., Ltd., grade C056, glass transition temperature Tg=10 ° C, solid The content is 45% by weight), and the weight ratio of the solid content of C056 to the total solid content of 1040 and 1005 is 3:1;

The adhesive layer slurry was sprayed onto the surface of the heat-resistant fiber layer in the polymer composite film F3 and on one side surface of the PTFE plate by spraying (temperature: 40 ° C), and then dried at 50 ° C, respectively, including The polymer composite film Sa11 of the adhesive layer and the porous self-crosslinking polymer film Sb11 on the PTFE plate, wherein the adhesive layer had a single-face density of 0.1 g/m ² and a single-sided thickness of 0.2 μm. The porous self-crosslinking polymer film Sb11 prepared as described above was found to have a porosity of 50%, a liquid absorption rate of 21%, and a conductivity of 7.31 mS/cm. And the ionic conductivity of the polymer composite film Sa11 was 7.22 mS/cm.

Example 29 (Preparation of PE base film-ceramic layer-heat resistant fiber layer-bonding layer four-layer structure polymer composite film)

(3) Forming a bonding layer: refer to Example 17, except that the bonding layer slurry further contains a chloropropene emulsion (Shanghai Ai Gao Chemical Co., Ltd., grade C056, glass transition temperature Tg=10 ° C, solid The content is 45% by weight), and the weight ratio of the solid content of C056 to the total solid content of 1040 and 1005 is 1:1;

The adhesive layer slurry was sprayed onto the surface of the heat resistant fiber layer in the polymer composite film F3 and on one side surface of the PTFE plate by spraying (temperature: 40 ° C), and then dried at 50 ° C to obtain The polymer composite film Sa12 including the adhesive layer and the porous self-crosslinking polymer film Sb12 on the PTFE plate, wherein the adhesive layer had a single face density of 0.1 g/m ² and a single face thickness of 0.2 μm. The porous self-crosslinking polymer film Sb12 prepared as described above was found to have a porosity of 46%, a liquid absorption rate of 18%, and a conductivity of 7.26 mS/cm. And the ionic conductivity of the polymer composite film Sa12 was 7.3 mS/cm.

Example 30 (Preparation of PE base film-ceramic layer-heat resistant fiber layer-bonding layer four-layer structure polymer composite film)

(3) forming a bonding layer: refer to Example 17, except that the self-crosslinking type pure acrylic emulsion 1005 is replaced by the same weight part of the self-crosslinking type pure acrylic emulsion 1020;

The adhesive layer paste was printed on the surface of the heat-resistant fiber layer in the polymer composite film F3 by a screen printing method (temperature: 75 ° C) and on one side surface of the PTFE plate, and then dried at 50 ° C. The polymer composite film Sa13 including the bonding layer and the porous self-crosslinking polymer film Sb13 on the PTFE plate were respectively obtained, wherein the bonding layer had a single-face density of 0.2 g/m ² and a single-sided thickness of 0.4 μm. . The porous self-crosslinking polymer film Sb13 prepared as described above was found to have a porosity of 47%, a liquid absorption rate of 160%, and a conductivity of 7.16 mS/cm. And the polymer composite film Sa13 was tested to have an ionic conductivity of 7.02 mS/cm.

Example 31 (Preparation of bonding layer-heat-resistant fiber layer-ceramic layer-PE base film-ceramic layer-heat-resistant fiber layer-bonding layer seven-layer structure polymer composite film)

(1) preparing a ceramic layer: same as in Example 16, forming a ceramic separator C9;

(2) Formation of heat-resistant fiber layer: In the same manner as in Example 17, a polymer composite film F17 was obtained.

(3) Formation of heat-resistant fiber layer: Referring to Example 17, a first adhesive layer (thickness of 0.1 μm) was first formed on the surface of the first heat-resistant fiber layer in the polymer composite film F17 by the method of Example 17, and then Further, a second adhesive layer (thickness: 0.1 μm) was formed on the surface of the second heat-resistant fiber layer in the polymer composite film F17 to obtain a polymer composite film Sa14. And the ionic conductivity of the polymer composite film Sa14 was 8.37 mS/cm.

The embodiments of the present disclosure have been described in detail above, but the present disclosure is not limited to the specific details in the above embodiments, and various simple modifications may be made to the technical solutions of the present disclosure within the scope of the technical idea of the present disclosure. It is within the scope of protection of the present disclosure.

It should be further noted that the specific technical features described in the above specific embodiments may be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not be further described in various possible combinations.

In addition, any combination of various embodiments of the present disclosure may be made as long as it does not deviate from the idea of the present disclosure, and should also be regarded as the disclosure of the present disclosure.

Claims

a polymer composite film,

Including a porous base film, and

a heat-resistant fiber layer covering at least one surface of the porous base film, wherein the material of the heat-resistant fiber layer contains both the first polymer material and the second polymer material; the first polymer material is a heat-resistant polymer material having a melting point of 180 ° C or higher; a melting point of the second polymer material lower than the first polymer material, and a liquid absorption rate of the second polymer material in an electrolyte solution at 25 ° C Above 40%, the error is ±5%.
The polymer composite film according to claim 1, wherein the first polymer material has a liquid absorption rate of less than 5% in an electrolytic solution at 25 ° C and an error of ± 5%.
The polymer composite film according to claim 1, wherein the first polymer material has a glass transition temperature of 100 ° C or higher.
The polymer composite film according to claim 1, wherein the second polymer material has a melting point of 100 to 150 ° C; alternatively, the second polymer material has a glass transition temperature of 25 ° C or lower.
The polymer composite film according to claim 1, wherein the second polymer material has a liquid absorption rate of from 40 to 100% at 25 ° C with an error of ± 5%.
The polymer composite film according to claim 1, wherein a material of the heat resistant fiber layer is a blend of the first polymer material and the second polymer material.
The polymer composite film according to claim 1, wherein a weight ratio of the first polymer material to the second polymer material in the heat resistant fiber layer is (0.5 to 10): 1, alternatively (1 to 5): 1, optional (1 to 3): 1.
The polymer composite film according to claim 1, wherein

The first polymer material is selected from one or more of polyetherimide, polyetheretherketone, polyethersulfone, polyamideimide, polyamic acid, and polyvinylpyrrolidone;

The second polymer material is selected from one or more of modified polyvinylidene fluoride, polyacrylate, polystyrene and polyethylene oxide; optionally, the modified polyvinylidene fluoride is a polyhedral Fluoroethylene-hexafluoropropylene; optionally, the polypropylene The enoate is selected from one or more of polymethyl acrylate, polyethyl acrylate, and polymethyl methacrylate.
The polymer composite film according to claim 8, wherein the first polymer material is polyetherimide, and the second polymer material is polyvinylidene fluoride-hexafluoropropylene; alternatively, The material of the heat resistant fiber layer is a blend of polyetherimide and polyvinylidene fluoride-hexafluoropropylene.
The polymer composite film according to claim 1, wherein a fiber diameter in the heat resistant fiber layer is 100 to 2000 nm, and the heat resistant fiber layer has a thickness of 0.5 to 30 μm.
The polymer composite film according to claim 1, wherein the heat resistant fiber layer has a porosity of 75% to 93% and an areal density of 0.2 to 15 g/m 2 .
The polymer composite film according to claim 1, wherein the porous base film is a polymer base film or a ceramic separator, the ceramic separator comprising a polymer base film and at least one side surface formed on the polymer base film Ceramic layer

Optionally, the porous base film is a ceramic separator, and the heat resistant fiber layer is located on a surface of the ceramic separator on a side where the ceramic layer is formed;

Optionally, the polymer based film is a polyolefin separator.
The polymer composite film according to claim 12, wherein the ceramic layer contains ceramic particles and a binder, and the surface density ρ of the ceramic layer at a thickness of 1 μm satisfies 1.8 mg/cm 2 < ρ 2.7 mg /cm 2 ; optionally satisfying 1.85 mg / cm 2 ≤ ρ ≤ 2.65 mg / cm 2 , optionally satisfying 1.9 mg / cm 2 ≤ ρ ≤ 2.6 mg / cm 2 ;

Optionally, the ceramic particles are selected from the group consisting of Al 2 O 3 , SiO 2 , BaSO 4 , BaO, TiO 2 , CuO, MgO, Mg(OH) 2 , LiAlO 2 , ZrO 2 , CNT, BN, SiC, Si 3 One or more of N 4 , WC, BC, AlN, Fe 2 O 3 , BaTiO 3 , MoS 2 , α-V 2 O 5 , PbTiO 3 , TiB 2 , CaSiO 3 , molecular sieve, clay, boehmite, and kaolin Optionally, the ceramic particles have an average particle diameter of 200 to 800 nm;

Optionally, the binder is a polyacrylate having a glass transition temperature of -40 ° C to 0 ° C;

Optionally, the ceramic layer has a single side thickness of 1-5 [mu]m.
The polymer composite film according to claim 13, wherein the binder is contained in an amount of 2 to 8 parts by weight based on 100 parts by weight of the ceramic particles;

Optionally, in the ceramic layer, 0.3 to 1 part by weight is further included with respect to 100 parts by weight of the ceramic particles. a dispersant, 0.5 to 1.8 parts by weight of a thickener, and 0 to 1.5 parts by weight of a surface treatment agent, and the number average molecular weight of the dispersant is 50,000 or less;

Optionally, in the ceramic layer, the content of the binder is 4-6 parts by weight with respect to 100 parts by weight of the ceramic particles, and the content of the dispersant is 0.4-0.8 parts by weight. The content of the thickener is 0.7-1.5 parts by weight, and the surface treatment agent is contained in an amount of 0.5-1.2 parts by weight;

Optionally, the dispersing agent is at least one of polyacrylate, aliphatic polyglycol ether, silicate, phosphate, and guar;

Optionally, the thickener is at least one of a polyacrylate, a polyacrylate copolymer, a polyvinylpyrrolidone, a cellulose derivative, and a polyacrylamide;

Alternatively, the surface treatment agent is 3-glycidylpropyltrimethoxysilane and/or 3-glycidylpropyltriethoxysilane.
The polymer composite film according to any one of claims 1 to 14, wherein the polymer composite film further comprises a bonding layer formed on at least one side of the polymer composite film The outermost surface of the surface, the bonding layer contains an acrylate crosslinked polymer and a styrene-acrylate crosslinked copolymer and/or a vinylidene fluoride-hexafluoropropylene copolymer, and the pores of the bonding layer The rate is 40 to 65%;

Optionally, the acrylate crosslinked polymer has a glass transition temperature of -20 ° C to 60 ° C, and the styrene-acrylate crosslinked copolymer has a glass transition temperature of -30 ° C to 50 ° C. The vinylidene fluoride-hexafluoropropylene copolymer has a glass transition temperature of from -65 ° C to -40 ° C.
The polymer composite film according to claim 15, wherein

The adhesive layer contains the acrylate crosslinked polymer and the styrene-acrylate crosslinked copolymer and does not contain the vinylidene fluoride-hexafluoropropylene copolymer, the acrylate crosslinks The weight ratio of the polymer to the styrene-acrylate crosslinked copolymer is 1: (0.05 to 2); or,

The adhesive layer contains the acrylate crosslinked polymer and the vinylidene fluoride-hexafluoropropylene copolymer and does not contain the styrene-acrylate crosslinked copolymer, and the acrylate crosslinks The weight ratio of the polymer to the vinylidene fluoride-hexafluoropropylene copolymer is 1: (0.3 to 25); or,

The adhesive layer contains the acrylate crosslinked polymer, the styrene-acrylate crosslinked copolymer, and the vinylidene fluoride-hexafluoropropylene copolymer, the acrylate crosslinked polymer The weight ratio of the styrene-acrylate crosslinked copolymer to the vinylidene fluoride-hexafluoropropylene copolymer is 1: (0.01 to 2): (0.3 to 5).
The polymer composite film according to claim 15, wherein said acrylate-based crosslinked polymer is first a mixture of an acrylate-based crosslinked polymer and a second acrylate-based cross-linking polymer and/or a third acrylate-based cross-linking polymer, or a second acrylate-based cross-linked polymer, or a third acrylate-based cross-linking polymer Copolymer

The first acrylate-based crosslinked polymer contains 70 to 80% by weight of a polymethyl methacrylate segment, 2 to 10% by weight of a polyethyl acrylate segment, and 10 to 20% by weight of polybutyl acrylate. a segment and 2 to 10% by weight of a polyacrylic acid segment, the second acrylate-based crosslinked polymer containing 30 to 40% by weight of a polymethyl methacrylate segment, and 2 to 10% by weight of a polyacrylic acid An ester segment, 50 to 60% by weight of a polybutyl acrylate segment and 2 to 10% by weight of a polyacrylic acid segment, the third acrylate-based crosslinked polymer containing 50 to 80% by weight of polymethacrylic acid a methyl ester segment, 2 to 10% by weight of a polyethyl acrylate segment, 15 to 40% by weight of a polybutyl acrylate segment, and 2 to 10% by weight of a polyacrylic acid segment; the first acrylate group The glass transition temperature of the bipolymer is from 50 ° C to 60 ° C, the glass transition temperature of the second acrylate crosslinked polymer is from -20 ° C to -5 ° C, and the third acrylate crosslinked polymerization The glass transition temperature of the object is 30 ° C to 50 ° C;

The styrene-acrylate crosslinked copolymer contains 40 to 50% by weight of a polystyrene segment, 5 to 15% by weight of a polymethyl methacrylate segment, and 2 to 10% by weight of a polyethyl acrylate. a segment, 30 to 40% by weight of a polybutyl acrylate segment and 2 to 10% by weight of a polyacrylic acid segment; the styrene-acrylate crosslinked copolymer has a glass transition temperature of 15 to 30 ° C;

The vinylidene fluoride-hexafluoropropylene copolymer contains 80 to 98% by weight of a polyvinylidene fluoride segment and 2 to 20% by weight of a polyhexafluoropropylene segment; and the vinylidene fluoride-hexafluoropropylene copolymer The glass transition temperature is -60 ° C to -40 ° C.
The polymer composite film according to claim 15, wherein

The adhesive layer contains a first acrylate-based crosslinked polymer, a second acrylate-based cross-linked polymer, and the styrene-acrylate cross-linked copolymer and does not contain the vinylidene fluoride-hexafluoropropylene a copolymer, and a weight ratio of the first acrylate-based crosslinked polymer, the second acrylate-based cross-linked polymer to the styrene-acrylate cross-linked copolymer is (5 to 10): 1: (10 to 13); or,

The bonding layer contains the first acrylate-based crosslinked polymer, the second acrylate-based cross-linked polymer, and the vinylidene fluoride-hexafluoropropylene copolymer and does not contain the styrene-acrylic acid An ester crosslinked copolymer, wherein the weight ratio of the first acrylate crosslinked polymer, the second acrylate crosslinked polymer to the vinylidene fluoride-hexafluoropropylene copolymer is (5 to 15) ): 1: (5 to 12); or,

The adhesive layer contains the second acrylate-based cross-linked polymer and the vinylidene fluoride-hexafluoropropylene copolymer and does not contain the styrene-acrylate cross-linked copolymer, the second acrylic acid The weight ratio of the ester crosslinked polymer to the vinylidene fluoride-hexafluoropropylene copolymer is 1: (5 to 20); or,

The bonding layer contains a second acrylate crosslinked polymer, the styrene-acrylate crosslinked copolymer, and a vinylidene fluoride-hexafluoropropylene copolymer, a weight ratio of the second acrylate crosslinked polymer, the styrene-acrylate crosslinked copolymer to the vinylidene fluoride-hexafluoropropylene copolymer Is 1: (0.5 to 2): (1 to 5); or,

The bonding layer contains a third acrylate-based crosslinked polymer, the styrene-acrylate cross-linked copolymer, and the vinylidene fluoride-hexafluoropropylene copolymer, and the third acrylate cross-linking The weight ratio of the polymer, the styrene-acrylate crosslinked copolymer to the vinylidene fluoride-hexafluoropropylene copolymer is 1: (0.5 to 2): (1 to 5); or,

The bonding layer contains the first acrylate-based cross-linked polymer, the second acrylate-based cross-linked polymer, the styrene-acrylate cross-linked copolymer, and the vinylidene fluoride-six a fluoropropylene copolymer, the first acrylate-based crosslinked polymer, the second acrylate-based cross-linked polymer, the styrene-acrylate cross-linked copolymer, and the vinylidene fluoride-hexafluorocarbon The weight ratio of the propylene copolymer is (10 to 15): 1: (0.5 to 2): (5 to 10);

Wherein the first acrylate-based crosslinked polymer contains 70 to 80% by weight of polymethyl methacrylate segments, 2 to 10% by weight of polyethyl acrylate segments, and 10 to 20% by weight of polyacrylic acid. a butyl ester segment and 2 to 10% by weight of a polyacrylic acid segment, the second acrylate-based crosslinked polymer containing 30 to 40% by weight of a polymethyl methacrylate segment, 2 to 10% by weight of a poly An ethyl acrylate segment, 50 to 60% by weight of a polybutyl acrylate segment and 2 to 10% by weight of a polyacrylic acid segment, the third acrylate crosslinked polymer containing 50 to 80% by weight of polymethyl a methyl acrylate segment, 2 to 10% by weight of a polyethyl acrylate segment, 15 to 40% by weight of a polybutyl acrylate segment, and 2 to 10% by weight of a polyacrylic acid segment, the styrene-acrylic acid The ester crosslinked copolymer contains 40 to 50% by weight of polystyrene segments, 5 to 15% by weight of polymethyl methacrylate segments, 2 to 10% by weight of polyethyl acrylate segments, 30 to 40% % by weight of polybutyl acrylate segment and 2 to 10% by weight of polyacrylic acid segment, said vinylidene fluoride-hexafluoropropyl The olefin copolymer contains 80 to 98% by weight of a polyvinylidene fluoride segment and 2 to 20% by weight of a polyhexafluoropropylene segment; the first acrylate-based crosslinked polymer has a glass transition temperature of 50 ° C to The glass transition temperature of the second acrylate crosslinked polymer is -20 ° C to -5 ° C at 60 ° C, and the glass transition temperature of the third acrylate crosslinked polymer is 30 ° C to 50 ° C The styrene-acrylate crosslinked copolymer has a glass transition temperature of 15 to 30 ° C, and the vinylidene fluoride-hexafluoropropylene copolymer has a glass transition temperature of -60 ° C to -40 ° C.
The polymer composite film according to claim 15, wherein the adhesive layer further contains at least one of an acrylonitrile-acrylate copolymer, a chloropropane copolymer, and a styrene-butadiene copolymer;

Optionally, when the adhesive layer further contains the acrylonitrile-acrylate copolymer, the weight ratio of the acrylonitrile-acrylate copolymer to the acrylate crosslinked polymer is (0.05 to 2): 1;

Optionally, when the tie layer further contains the chloropropane copolymer, the weight ratio of the chloropropane copolymer to the acrylate cross-linking polymer is (0.15 to 7): 1;

Optionally, when the bonding layer further contains the styrene-butadiene copolymer, the styrene-butadiene copolymer and the acrylate The weight ratio of the cross-linked polymer is (0.05 to 2): 1.
The polymer composite film according to claim 15, wherein the bonding layer has a single face density of 0.05 to 0.9 mg/cm 2 ; and the bonding layer has a single face thickness of 0.1 to 1 μm.
A method for preparing a polymer composite membrane, comprising the steps of:

S1, providing a porous base film;

S2, preparing a spinning solution containing a first polymer material and a second polymer material, and forming the heat-resistant fiber layer on at least one side surface of the porous base film by electrospinning; The first polymer material is a heat resistant polymer material having a melting point of 180 ° C or higher; the melting point of the second polymer material is lower than the first polymer material, and the second polymer material is electrolyzed at 25 ° C The liquid absorption rate in the liquid is above 40%, and the error is ±5%;

Optionally, the first polymer material has a liquid absorption rate of less than 5% in an electrolyte at 25 ° C, and an error of ± 5%;

Optionally, the first polymer material has a glass transition temperature of 100 ° C or higher;

Optionally, the second polymer material has a melting point of 100 to 150 ° C; optionally, the second polymer material has a glass transition temperature of 25 ° C or less;

Optionally, the second polymer material has a liquid absorption rate of 40 to 100% at 25 ° C with an error of ± 5%.
The preparation method according to claim 21, wherein the weight ratio of the first polymer material to the second polymer material in the spinning polymer in the step S2 is (0.5 to 10): 1, alternatively (1 to 5): 1, optional (1 to 3): 1.
The preparation method according to claim 21, wherein in the step S2,

The first polymer material is selected from one or more of polyetherimide, polyetheretherketone, polyethersulfone, polyamideimide, polyamic acid, and polyvinylpyrrolidone;

The second polymer material is selected from one or more of modified polyvinylidene fluoride, polyacrylate, polystyrene and polyethylene oxide; optionally, the modified polyvinylidene fluoride is a polyhedral Fluoroethylene-hexafluoropropylene; alternatively, the polyacrylate is selected from one or more of polymethyl acrylate, polyethyl acrylate, and polymethyl methacrylate.
The preparation method according to claim 21, wherein the step S2 comprises:

S201, separately preparing a spinning solution A containing the first polymer material and a spinning solution B containing the second polymer material;

S202, simultaneously performing electrospinning using the spinning solution A and the spinning solution B to form the heat resistant fiber layer.
The preparation method according to claim 21, wherein the step S2 comprises:

S211, blending the first polymer material and the second polymer material to form a blend; and preparing a spinning solution containing the blend;

S212, performing electrospinning using the spinning solution to form the heat resistant fiber layer.
The production method according to claim 21, further comprising, after completion of the electrospinning, laminating at a pressure of 50 to 120 ° C and a pressure of 0.5 to 10 MPa.
The production method according to claim 21, wherein said porous base film is a ceramic separator, and said ceramic separator comprises a polymer base film and a ceramic layer on a surface of said polymer base film; said heat resistant fiber layer is formed On the surface of the ceramic layer in the ceramic diaphragm.
The preparation method according to claim 27, wherein the method for preparing the ceramic separator in the step S1 comprises:

S11, providing a polymer base film;

S12, mixing ceramic particles, a binder, a dispersing agent and a thickener according to a weight ratio of 100: (2 to 8): (0.3 to 1): (0.5 to 1.8) to obtain a ceramic layer slurry, and The ceramic layer slurry is coated on at least one side surface of the polymer base film, and dried to obtain the ceramic layer; wherein the dispersing agent has a number average molecular weight of 50,000 or less;

Optionally, in the step S12, the stirring speed is 3000 to 10000 rpm, optionally 3000-9000 rpm; the stirring time is 30 to 120 min;

Optionally, in the step S12, the ceramic particles, the binder, the dispersing agent and the thickener are in a weight ratio of 100: (4 to 6): (0.4 to 0.8): ( Mix in a ratio of 0.7 to 15).
The preparation method according to claim 28, wherein in the step S12,

The ceramic particles are selected from the group consisting of Al 2 O 3 , SiO 2 , BaSO 4 , BaO, TiO 2 , CuO, MgO, Mg(OH) 2 , LiAlO 2 , ZrO 2 , CNT, BN, SiC, Si 3 N 4 , WC At least one of BC, AlN, Fe 2 O 3 , BaTiO 3 , MoS 2 , α-V 2 O 5 , PbTiO 3 , TiB 2 , CaSiO 3 , molecular sieve, clay, boehmite, and kaolin, optionally, The ceramic particles have an average particle diameter of 200 to 800 nm, optionally 300 to 600 nm;

The binder is a polyacrylate having a glass transition temperature of -40 ° C to 0 ° C;

The dispersing agent is at least one of polyacrylate, aliphatic polyglycol ether, silicate, phosphate and guar;

The thickener is at least one of a polyacrylate, a polyacrylate copolymer, a polyvinylpyrrolidone, a cellulose derivative, and a polyacrylamide.
The preparation method according to claim 28, wherein the ceramic layer slurry obtained by mixing in the step S12 further contains a surface treatment agent, and the surface treatment agent is 3-glycidylpropyltrimethoxysilane and/or 3-glycidylpropyltriethoxysilane;

Alternatively, the surface treatment agent is used in an amount of 1.5 parts by weight or less, alternatively 0.5 to 1.2 parts by weight, per 100 parts by weight of the ceramic particles.
The preparation method according to any one of claims 21 to 30, further comprising:

S3. Forming a bonding layer on at least one surface of the composite film obtained in step S2.
The preparation method according to claim 31, wherein the step S3 comprises:

a slurry containing a self-crosslinking type pure acrylic emulsion and a self-crosslinking type styrene-acrylic emulsion and/or a copolymerized emulsion of vinylidene fluoride and hexafluoropropylene is attached to at least one surface of the composite film obtained by the step S2, And then drying to form a bonding layer having a porosity of 40 to 65% on at least one side surface of the porous base film;

Optionally, the acrylate-based crosslinked polymer in the self-crosslinking type pure acrylic emulsion has a glass transition temperature of -20 ° C to 60 ° C, and the styrene-acrylic acid in the self-crosslinking type styrene-acrylic emulsion The glass transition temperature of the ester crosslinked copolymer is from -30 ° C to 50 ° C, and the glass transition temperature of the vinylidene fluoride-hexafluoropropylene copolymer in the copolymer emulsion of vinylidene fluoride and hexafluoropropylene is -65 °C to -40 ° C.
The method according to claim 32, wherein in said step S3,

The slurry comprises a self-crosslinking type pure acrylic emulsion and a self-crosslinking type styrene-acrylic emulsion and does not contain a copolymerized emulsion of vinylidene fluoride and hexafluoropropylene, the self-crosslinking type pure acrylic emulsion and self-crosslinking type styrene-acrylic The weight ratio of the solid content of the emulsion is 1: (0.05 to 2); or,

The slurry comprises a self-crosslinking type pure acrylic emulsion and a copolymerized emulsion of vinylidene fluoride and hexafluoropropylene and does not contain a self-crosslinking type styrene-acrylic emulsion, the self-crosslinking type pure acrylic emulsion and vinylidene fluoride and hexafluorocarbon The weight ratio of the solid content of the copolymer emulsion of propylene is 1: (0.3 to 25); or,

The slurry comprises a self-crosslinking type pure acrylic emulsion, a self-crosslinking type styrene-acrylic emulsion, a copolymerized emulsion of vinylidene fluoride and hexafluoropropylene. The weight ratio of the solid content of the self-crosslinking type pure acrylic emulsion, self-crosslinking type styrene-acrylic emulsion, vinylidene fluoride and hexafluoropropylene is 1: (0.01 to 2): (0.3 to 5) .
The method according to claim 32, wherein in said step S3,

The self-crosslinking type pure acrylic emulsion is a mixture of the first self-crosslinking type pure acrylic emulsion and the second self-crosslinking type pure acrylic emulsion and/or the third self-crosslinking type pure acrylic emulsion, or is the second self-crossing a combined pure acrylic emulsion, or a third self-crosslinking type pure acrylic emulsion;

The acrylate crosslinked polymer in the first self-crosslinking type pure acrylic emulsion contains 70 to 80% by weight of a polymethyl methacrylate segment, 2 to 10% by weight of a polyethyl acrylate segment, 10 Up to 20% by weight of the polybutyl acrylate segment and 2 to 10% by weight of the polyacrylic acid segment, and the acrylate crosslinked polymer in the second self-crosslinking type pure acrylic emulsion contains 30 to 40% by weight a polymethyl methacrylate segment, 2 to 10% by weight of a polyethyl acrylate segment, 50 to 60% by weight of a polybutyl acrylate segment, and 2 to 10% by weight of a polyacrylic acid segment, the third The acrylate crosslinked polymer in the self-crosslinking type pure acrylic emulsion contains 50 to 80% by weight of polymethyl methacrylate segments, 2 to 10% by weight of polyethyl acrylate segments, 15 to 40% by weight a polybutyl acrylate segment and 2 to 10% by weight of a polyacrylic acid segment; the acrylate crosslinked polymer in the first self-crosslinking pure acrylic emulsion has a glass transition temperature of 50 ° C to 60 ° C The glass transition temperature of the acrylate crosslinked polymer in the second self-crosslinking type pure acrylic emulsion is -20 ° C The glass transition temperature of the acrylate crosslinked polymer in the third self-crosslinking type pure acrylic emulsion is from 30 ° C to 50 ° C;

The styrene-acrylate crosslinked copolymer in the self-crosslinking type styrene-acrylic emulsion contains 40 to 50% by weight of a polystyrene segment, 5 to 15% by weight of a polymethyl methacrylate segment, 2 Up to 10% by weight of polyethyl acrylate segment, 30 to 40% by weight of polybutyl acrylate segment and 2 to 10% by weight of polyacrylic acid segment; glass of said styrene-acrylate crosslinked copolymer The transformation temperature is 15 to 30 ° C;

The vinylidene fluoride-hexafluoropropylene copolymer in the copolymer emulsion of vinylidene fluoride and hexafluoropropylene contains 80 to 98% by weight of a polyvinylidene fluoride segment and 2 to 20% by weight of a polyhexafluoropropylene segment; The vinylidene fluoride-hexafluoropropylene copolymer has a glass transition temperature of from -60 ° C to -40 ° C.
The method according to claim 32, wherein in said step S3,

The slurry comprises a first self-crosslinking type pure acrylic emulsion, a second self-crosslinking type pure acrylic emulsion, and the self-crosslinking type styrene-acrylic emulsion, and does not contain the copolymerized emulsion of the vinylidene fluoride and hexafluoropropylene. The weight ratio of the first self-crosslinking type pure acrylic emulsion, the second self-crosslinking type pure acrylic emulsion and the self-crosslinking type styrene-acrylic emulsion is (5 to 10): 1: (10) To 13); or,

The slurry contains the first self-crosslinking type pure acrylic emulsion, the second self-crosslinking type pure acrylic emulsion, and the copolymerized emulsion of the vinylidene fluoride and hexafluoropropylene and does not contain the self-crosslinking type Styrene-acrylic emulsion, the first self-crosslinking type pure acrylic emulsion, The weight ratio of the solid content of the second self-crosslinking type pure acrylic emulsion to the copolymerized emulsion of the vinylidene fluoride and hexafluoropropylene is (5 to 15): 1: (5 to 12);

The slurry contains the second self-crosslinking type pure acrylic emulsion and a copolymerized emulsion of the vinylidene fluoride and hexafluoropropylene and does not contain the self-crosslinking type styrene-acrylic emulsion, and the second self-crosslinking type The weight ratio of the pure acrylic emulsion to the copolymerized emulsion of the vinylidene fluoride and hexafluoropropylene is 1: (5 to 20); or,

The slurry comprises the second self-crosslinking type pure acrylic emulsion, the self-crosslinking type styrene-acrylic emulsion, and a copolymerized emulsion of the vinylidene fluoride and hexafluoropropylene, the second self-crosslinking type pure acrylic The weight ratio of the emulsion, the self-crosslinking type styrene-acrylic emulsion and the copolymerized emulsion of the vinylidene fluoride and hexafluoropropylene is 1: (0.5 to 2): (1 to 5);

The slurry comprises a third self-crosslinking type pure acrylic emulsion, the self-crosslinking type styrene-acrylic emulsion, and a copolymerized emulsion of the vinylidene fluoride and hexafluoropropylene, the third self-crosslinking type pure acrylic emulsion, The weight ratio of the self-crosslinking type styrene-acrylic emulsion to the copolymerized emulsion of the vinylidene fluoride and hexafluoropropylene is 1: (0.5 to 2): (1 to 5);

The slurry comprises the first self-crosslinking type pure acrylic emulsion, the second self-crosslinking type pure acrylic emulsion, the self-crosslinking type styrene-acrylic emulsion, and copolymerization of the vinylidene fluoride and hexafluoropropylene An emulsion, a solidification of the first self-crosslinking type pure acrylic emulsion, the second self-crosslinking type pure acrylic emulsion, the self-crosslinking type styrene-acrylic emulsion and the copolymerized emulsion of the vinylidene fluoride and hexafluoropropylene The weight ratio of the content is (10 to 15): 1: (0.5 to 2): (5 to 10);

The acrylate crosslinked polymer in the first self-crosslinking type pure acrylic emulsion contains 70 to 80% by weight of a polymethyl methacrylate segment, 2 to 10% by weight of a polyethyl acrylate segment, 10 Up to 20% by weight of the polybutyl acrylate segment and 2 to 10% by weight of the polyacrylic acid segment, and the acrylate crosslinked polymer in the second self-crosslinking type pure acrylic emulsion contains 30 to 40% by weight a polymethyl methacrylate segment, 2 to 10% by weight of a polyethyl acrylate segment, 50 to 60% by weight of a polybutyl acrylate segment, and 2 to 10% by weight of a polyacrylic acid segment, the third The acrylate crosslinked polymer in the self-crosslinking type pure acrylic emulsion contains 50 to 80% by weight of polymethyl methacrylate segments, 2 to 10% by weight of polyethyl acrylate segments, 15 to 40% by weight a polybutyl acrylate segment and 2 to 10% by weight of a polyacrylic acid segment, the styrene-acrylate crosslinked copolymer in the self-crosslinking styrene-acrylic emulsion containing 40 to 50% by weight of polystyrene Segment, 5 to 15% by weight of polymethyl methacrylate segment, 2 to 10% by weight of polyethyl acrylate segment, 30 Up to 40% by weight of the polybutyl acrylate segment and 2 to 10% by weight of the polyacrylic acid segment, the vinylidene fluoride-hexafluoropropylene copolymer in the copolymer emulsion of vinylidene fluoride and hexafluoropropylene contains 80 to 98 a wt% polyvinylidene fluoride segment and 2 to 20% by weight of a polyhexafluoropropylene segment; the acrylate crosslinked polymer in the first self-crosslinking type pure acrylic emulsion has a glass transition temperature of 50 The glass transition temperature of the acrylate crosslinked polymer in the second self-crosslinking type pure acrylic emulsion is from -20 ° C to -5 ° C from ° C to 60 ° C, and the third self-crosslinking type pure acrylic emulsion The acrylate-based crosslinked polymer has a glass transition temperature of 30 ° C to 50 ° C, and the styrene-acrylate cross-linked copolymer has a glass transition temperature of 15 to 30 ° C, and the vinylidene fluoride- The hexafluoropropylene copolymer has a glass transition temperature of from -60 ° C to -40 ° C.
The method according to claim 32, wherein in said step S3,

The slurry further comprises at least one of a copolymer emulsion of acrylonitrile and acrylate, a chloropropene emulsion and a styrene-butadiene latex;

Optionally, when the slurry further contains the copolymerized emulsion of acrylonitrile and acrylate, the weight ratio of the copolymerized emulsion of acrylonitrile and acrylate to the solid content of the self-crosslinking pure acrylic emulsion (0.05 to 2): 1;

Optionally, when the slurry further contains the chloropropene emulsion, the weight ratio of the chloropropene emulsion to the solid content of the self-crosslinking pure acrylic emulsion is (0.15 to 7): 1;

Optionally, when the slurry further contains the styrene-butadiene latex, the weight ratio of the solid content of the styrene-butadiene latex to the self-crosslinking pure acrylic emulsion is (0.05 to 2):1.
The method according to claim 32, wherein the method of attaching is a spray coating method and/or a screen printing method; the operating temperatures of the spray coating method and the screen printing method are each independently 30 to 80 ° C; The drying temperature is 30 to 80 °C.
A polymer composite film produced by the method according to any one of claims 21 to 37.
A lithium ion battery comprising a positive electrode, a negative electrode, and a battery separator between the positive electrode and the negative electrode, the battery separator being the polymer composite film according to any one of claims 1 to 20 and 38.